So, I'm about 250 lbs and my SO is around 220. He's athletic and slim and we always do missionary, but I'm SO SCARED of being on top. He's always been on top and never has pressured me, but I feel bad because I feel like I don't contribute.

Has anybody else had the same fear? For some reason I feel like I won't be able to sit on his dick without putting a lot of pressure on him. Plus, my upper body strength is terribly weak.

Help please!!