Bbw riding tips

I want to be on top more often but i can’t figure this shit out. We struggle for me to even get it in and once we do when i move he just slips out. Is my body or what i’m doing with it the problem or is it his penis size or his belly? We’re both big people but it’s incredibly frustrating. I can barely move before he slips out and it makes me super self conscious and sometimes i wanna cry before we can even get started because just getting it in when i’m on top is such an ordeal. Someone please help me on how i can make this work for both of us because i really want to.