Plus size positions?

I'm curious to find out some new positions my so and I can try. I'm 6'1" and around 280 and he's 6'1" and over 300 and isn't the most well endowed we always have sex with me on top cause that's the only way I can feel it really good. He tries to be on top but at that angle it doesn't like to stay in and he moves really slow and it's just not enjoyable to me. And doggy is basically out. Help please?