I hate having sex?

I recently lost my virginity (age 21) to someone that I love and that loves me, it was fully consensual etc. I love him to bits but I absolutely hate having sex and can't wait for it to be over. It hurts and is physically uncomfortable and I don't know what to do with my legs - they always end up trying to push him out. I'm definitely straight and not asexual as I want to enjoy sex and I do get turned on and enjoy foreplay. Help!