Is it normal to try to stick my penis up my own butt

Just ask about the strap on.

i try sometimes, but it is definately possible, you need a large dick, and a curve

Ask her about the strap on. It isn't gay unless its another dude fucking you. If the strap on is not an option purchase an anal dildo.

borrow your gf's dildo

Dude... You took it way to literally when i said " go fuck yourself"

Look up pegging with her

well that's enough internet for today

I have spent quite some time trying, but never succeeded.
I've pretty much given up now.