Overcoming weight anxiety

So I've come to realize that when my man and I are really into our make out sessions, he likes to pull me on top of him. Which is fine, I actually love when he does this. The issue is that I can't seem to ignore the anxiety that I'm too heavy. I'm not incredibly heavy, but I am curvy, and my boyfriend is on the skinnier side. To be honest, I really want to take some more control the next time things get heated and sit on his lap (facing him so I can still wrap my body around him and continue to kiss his neck) I just don't want to feel insecure when doing so. Do any of you have tips on overcoming/ignoring weight anxiety??