How do I (27f) get comfortable sitting on his (30m) face?

I (27F) have been having very very fun and intimate sex with a man (30m) for about 4 months now. I love riding him and letting him see my whole body, love when he goes down on me, there’s only 1 thing I get self conscious about in bed. When I ride his face he always wants me to sit down more than just hovering, and it takes me out of the moment because then all im thinking is “how fat do I feel to him putting my weight on him” “I must be so heavy there’s no way he’s enjoying this.” I’m not a heavy woman, I’m average with some curves, but I still just can’t orgasm this way and he loves it. Tips for warming up to it and getting more comfortable actually sitting and not hovering??