Pushing Air In Stomach

So during sex sometimes, with each movement it feels like my boyfriend is pushing air in my stomach. Sometimes it will get so bad to where you can actually hear it. Like something is moving around in there. How can we prevent this? Sometimes itll be so bad doesnt matter the position and I have to tell him we need to stop with penetration and switch to oral. Also there will be times where it's difficult for him to put it in. Like something is blocking the way of his penis going into my vagina. And this is a complete different feeling from me not being wet enough or from me being tight.