Vaginal Sex Hurts Still

I am struggling to enjoy vaginal sex, using a dildo of course, and was curious kinda what it would take for my body to get used to it. I have only experienced vaginal sex a handful of times with my girlfriend but each time it doesn’t really get much butter. It hurts the most when the dildo pulls out. Ive literally just sat on my girlfriend with a strap on and tried to get my body used to having something inside me but I am getting impatient atp 😅

Any advice anyone has or experience or anything at all I would greatly appreciate!