I'll answer this as I would years ago when I still believed in God. Although many of the details are not official LDS doctrine, the Mormons I taught it to tended to accept it without being able to identify how it contradicted, but only went along with, what the LDS church teaches.
God has always existed as something, but not always as God. Like us, Elohim was originally an intelligence, a being of unspecified properties other than its ability to learn and status of being uncreated. The spiritual parents of Elohim (the male parent being God at the time) gave a spiritual body to Elohim. Spiritual matter is "purer" and "more refined" than physical matter. Spiritual bodies look like human bodies (bipedal, two eyes, two ears, hair, etc.). This spiritual personage, Elohim, later obtained a physical body on an earth-like planet and served as a savior for many of Elohim's father's other spiritual children who weren't as perfect as he was, just like Jesus did this later for us who are supposed to be spiritual children of Elohim (and one of his female wives).
In this doctrine Human existence becomes one important part in the eternal progression of intelligences to spirits to spirits within imperfect human bodies (where we are right now) to resurrected glorified spirit+physical bodies and perhaps even beyond.
Mormon theology tries to answer the question "Where did God come from?" by saying God had a father just like Jesus did. This begs the question of where the first God came from.
To deal with this I wrote a Freshman Honors paper in which I extrapolated from some LDS scripture to explain how the first God might have come to be. I suggested that since intelligences naturally "cleave" to other intelligences (sort of like gravity or EM) according to the Doctrine and Covenants then maybe intelligences and space was all there was in the beginning, both uncreated. As intelligences joined together they became more complex. At some point one or more of them became self-aware. They continued to aggregrate intelligences to themselves and progress in learning as they observed their surroundings (what little there was to learn).
Eventually one of these intelligences, the most advanced, changed its state temporarily into spiritual matter, a different arrangement of intelligences with additional learning abilities (why would merely changing the structure produce improved learning? I don't know).
This intelligence, I'll call Spirit-1, realized he could learn more with the spiritual body than merely as an intelligence and eventually permanently made the change and possibly taught other intelligences how to do it. This might have been the first God, God-1
Later one of these spirit+intelligences discovered that by partially joining with a different arrangement of intelligences, what we would call physical matter, allowed for additional experiences. One could "feel" in ways a spirit couldn't. According to this idea physical matter is composed of individual intelligences that aren't tied so closely that they are a single large intelligence. This is Physical-1. This might have been the same as Spirit-1, or someone else. Perhaps this was God-1.
The laws of nature of our universe exist according to this idea because these intelligences obey a set of rules given them by God. Miracles exist because God can change the rules if He chooses. Satanic miracles can occur, but be less powerful than God's, because intelligences tend to respect their superiors whether their the best or not.
It took a very long time for this early process of changing from single small intelligences to large intelligences (close aggregates of intelligences) to spirit bodies (less closely arranged intelligences housing a large intelligence) to physical bodies housing spirit + intelligences. After the early ones figured out how to do it, they began to teach it to others and developed ways to speed up the process. Some of these teachers were better than others. The best of the teachers was sought by the intelligences to be their spiritual father, to take them from being mere intelligences to having spirit bodies. Maybe this was the same as Spirit-1 and Physical-1 and perhaps was the first God.
Since that time the process has been streamlined. Now planets are built to make it easier to build physical bodies and give the spirits experience. Intelligences are being given spirit bodies at a much faster rate. As the resurrected beings continue to develop maybe they change state to something more advanced and let the younger ones take over.
The first physical universe was created by a later group of Gods who decided it would be more efficient than the earlier methods of obtaining physical bodies. This would give room for the various Gods to have their own planets to use. Other universes could be built in other parts of eternal space. The universe is built by organizing the intelligences into physical structures. Our universe may be the first or only one of many.
In this model, Elohim becomes the current God of the Earth and other planets. Maybe He's the God of the Milky Way Galaxy only, with Kolob (the nearest celestial sphere to the sphere of glass He dwells on) being near the center or on the edge of the galaxy. His spiritual brothers would be the Gods of other Galaxies or star clusters. Jesus is the first spiritual son of Elohim and was the primary organizer of the Earth and Solar System. Worthy LDS men and women will become Gods as well and eventually build their own worlds populating them with intelligences they made into Spirits.
It's a pretty good investment to dedicate much of your Earthly life and 10%+ of your income to the LDS Church in exchange for the opportunity to be a God, don't you think?
The less worthy won't be permitted or sought for as spiritual parents by the nearly infinite number of intelligences existing in the unorganized eternal space.
In this model everything is just intelligences, space and communicating particles similar to photons. Self-aware intelligences are just large closely-combined smaller intelligences. Spirit matter is reorganized small intelligences used to house the large intelligences. Physical matter (like quarks and electrons) are just organized intelligences. The visible universe is just that part of eternal space where the intelligences have been specially organized to form physical matter.
In this model, there was not always a God, but we and God always existed as intelligences.
The reason the pre-Earth born spirits look like Homo Sapiens is by design. By chance the first physical body acceptable to the Gods that evolved on a planet long ago on a different planet was a human-like body. By choice, the human form has been encouraged to evolve ever since on other planets. If non-human aliens are discovered, this theory would have to be discarded (yes!) or changed.
Sexual form is given to the intelligences when they become spirits based on whether their characterists better match that sex. "Sexually confused" people on earth were borderline spirit cases.
If you're curious what my teachers thought of the essay, I'll tell you (even if you're not curious.) The Honors Colloquium instructor who read it, Reid Nibley, the musically-talented younger brother of the famous LDS apologist Hugh Nibley, said he didn't like my thesis because it made the origin of the Gods mechanistic. Well, what do you want? If you won't accept that God was always God, either He was made by another God with no break (As Alex would say: it's turtles all the way down) or the first one came about by natural processes. What other options are there?
There's some more I could say, but I worry that I've either made someone ill or they've decided I'm a prophet and should establish a new religion. Hopefully, the rest of you just thought it was entertaining reading.
Did that answer your question about whether God existed forever from one Mormon perspective or was the seemingly "forever" nature of my post too much?