Big girl small man

I recently started dating someone a lot smaller than me. For reference I am 5’2 and 190lbs. I carry all my weight in my stomach and arms. He is taller than me and weighs around 150 and is like a twig compared to me. I have always dated men bigger than me. I’m having a problem adjusting. I have never got naked in front of him, I keep clothes on during sex. I think it also gets me that I’ve never had him make a comment on how he likes my body. How do you overcome this insecurity and any tips for sex for a big girl, small man are greatly appreciated!