Quote Originally Posted by The Glyphstone
My five planes are Earth, Water, Air, Life, and Death, with Life combining plants/nature and parts of the Positive Energy Plane into its vision and Death including parts of the Negative Energy plane.

As far as sorcerers, being pacted to an elemental would give an affinity for that sort of spell or magic, and possibly penalties to 'opposed' elements. So that Firepact sorcerer would find that fire spells are easier to learn and more powerful, while water-aligned spells might be weaker (indecisive here).
Quote Originally Posted by The Glyphstone
The Plane of Life is a massive, primordial forest filled with endless layers of trees and jungle canopies that stack endlessly upon each other, with no discernable ceiling or floor to the growths. The elementals here are more varied in shape and form than any other plane, manifesting as a limitless variety of plants and animals that grow, crawl, and fly between the interwoven branches. Many are predatory as well, making them the most outwardly dangerous of any elemental plane's natives in contrast to the comparatively welcoming environment.
[...]
The Plane of Dreams is associated with Future, infinite branching possibilities of what might yet become Present.
[...]
At the very tip of the pyramidal arrangement is the Plane of Faerie, the most fragile and insubstantial of planes. Much like its fae inhabitants, Faerie is an ephemeral and ever-changing place of illusions and phantasms made real. It is highly prone to altering itself in response to the emotions and willpower of sapient minds within it, at time seeming to sport a deliberately malevolent nature and other times merely whimsical. Natural portals between Faerie and the Material Plane open and close seemingly at random, though the magical power of the greater Fae lords allows them to heavily influence such formations. The Fae are also prone to traipsing though Dream and Memory at will, drinking greedily of the sights and emotions they encounter.
It's interesting to see someone use a slightly different elemental system other than the Western four, the Chinese five, the Japanese five, or the video game six (the classic four plus light and darkness), but I see a few potential issues:

1) I note that the Plane of Faerie is much like the classic take on the Plane of Dreams (responds to mortals' thoughts, possibly "alive" in some way, etc.) while the Plane of Life is much like classic Faerie (very nature-y, deceptively "safe" compared to the Material, etc.), so anyone to whom you give a quick Cosmology 101 overview is likely to mix those up really easily, and the fact that the fey are in Dream all the time but can't easily access the nature-y plane is a bit odd.

2) I also note that you haven't explained where Fire fits into the elemental planes despite mentioning dragons and firepact sorcerers, and fire doesn't fit as a good intermediary or para-element to any of the five in the way that it could if you were using, say, Light instead of Life so Fire could be Light/Air or something.

3) Going with Life and Death as elements instead of Positive and Negative Energy seems a bit strange if you're trying to emphasize Order and Chaos, since the "positive energy is the generative structuring force, negative energy is the dissolving entropic force, and the two of them form a big cosmic battery keeping the universe running" setup from the Great Wheel wonderfully reinforces the message that both too much Law and too much Chaos are bad.

Plus, as it stands, the planes of Life and Death don't feel much like their own elemental planes, since the jungle in Life feels like it should be an Air+Earth+Water paraplane (because trees grow out of the earth and get rained on and respire) even if theoretically it's trees upon trees upon trees forever, and the winds-or-sands-or-ice of Death feel like quasielements of Air, Earth, and Water. In fact, if you were to just give me descriptions of each plane and ask me to match them to their names, I might assume that the bountiful nature of Life is actually Faerie and the subjective experience of Death is actually Memory, and then match Life with the First World and its bountiful lifeforms and Death with the Second World and its crystalline lifelessness.

So, if I could suggest two slight tweaks to the cosmology:

1) Instead of having the two temporal planes orbit the Material, have them orbit Faerie and make Faerie explicitly the plane of the Present the same way that Dream is Future and Memory is Past. Describing the fey as actors in a grand cosmic play who always live in the moment, care nothing for their past, and don't think of their future makes the Faerie/Dream and Faerie/Memory ties much more understandable, and three ephemeral temporal planes ties in with 3 being the number of power without stability.

2a) Associate positive and negative energy with the First and Second Worlds. Whether it's First = positive (because being infused with the generative power of positive energy allows protean beings to exist with their aberrant biology) and Second = negative (because being infused with the stasis of uniform entropy strongly resists change) or First = negative (because being infused with the decay of negative energy doesn't allow the inhabitants to maintain singular forms) and Second = positive (because being infused with the structure of positive energy allows the shards of a broken world to survive indefinitely) is up to you--and whether it's one or the other or somehow both could be an in-world debate between scholars, since no one can go there and check.

2b) With positive and negative energy moved around, rename Life to Wood and exchange its actual animals with animal-like wood elementals (which keeps the "infinite jungle" theme without it feeling like a mishmash) and Death with...well, it's hard to say, because the multiple-choice existence thing is a really good fit for the temporal planes and not so much for an elemental plane, so perhaps Void might work: it kills you when you go there because, y'know, lack of existence, and if someone somehow does manage to go there the only thing they find is what they bring with them.

That still leaves you without an explicit Fire element, but having Fire come from Wood or Wood/Air because trees burn (in the same way Wood gives rise to Air in the Wu Xing because trees wave in the wind) is probably good enough.