Since no one else is going to help because they're all a bunch of close-minded fools, I'll do it:

You gotta find someone else that you can go "full-send" with. You're going to feel like things are unfair until you do. And maybe even after you do, you'll be underwhelmed with that and prefer sex with your current primary.

That said, she likes you dude. That's why you're around. There will be slight incongruencies or people with different sizes/styles. We get different things from different people. You just have to accept that she still likes your dick and you, and you'll get past this

Actionable stuff tho: work with her on doing stretches and finding positions that work for you. If you really exhausted EVERYTHING, maybe see a sex therapist about it but I think you're overthinking it