When I first started trimming I got a piece of advice that I took to heart and I will pass it along to you in case your horse has sensitive feet. She might be a lot happier if you didn't par out her sole. I used to do that too- something about avoiding sole pressure. Then I learned that the sole is there to protect the inner structures and a horse's sole is not very thick at all! So any live sole you take off is actually making her feet more prone to abcesses, bruising or worse. That sole actually protects the coffin bone and that is something you want to protect.
Over the years I have really come to the conclusion that when trimming, less is more.
Anyway, maybe she has tough feet and it isn't an issue. But if it is, try leaving her sole alone. I've gotten so I never remove sole unless it is flaking out on it's own. Then I might help it along. But I never trim up the sole otherwise.
And although you don't want to purposely leave the heels uneven, I also respect the natural crookedness of the horse and don't try to "fix" conformation issues. You want the foot to land flat even if that means she looks pigeon toed in front or toed out behind. I find most horses are crooked in various ways and I've talked to my vet about it and he really believes you should not try to fix conformation flaws on an adult horse. You can cause the arthritis and lameness issues you are trying to avoid.
Anyhow, that is just some advice. Not sure if everyone agrees with it.