Sex again after years

Geli
So I just got into a relationship after 2 years of being single. For whatever reason, I just never found a real reason to hook up. Now that I'm with this dude we obviously are having sex and it's been almost 2 years since I've done it (no judgment) and I know it's going to be a tough ride (all the puns!!!) getting back into the swing of things but how long is it normal to feel discomfort? I feel like he's bigger than the average dude and I'm smaller than the average chick and it's gotten better but if he hits it from the back I feel it all up in my guts and it hurts. Is this normal and how can I fix it. Please please help!