Tmi sex with baby dad

So today we had sex for the first time in a while . we just haven't had time to really. But a while into it and we have made it into missionary and I was kind of.holding my stomach and I noticed when he would go in I could feel something push up against my hand and so I freaked out and I showed him.he freaked out . I assume it was him just pushing up against everything and shifting it to go up . should I be worried tho ? Is sex still safe ?