How do you have a penetrative orgasm?

I’ve never had one. Whenever my ex and I had sex I would have to use my hand on my clit to have an orgasm. He felt good inside me, that wasn’t the problem, it’s just that I could never quite reach that climax from penetration alone.

I know my body isn’t made that way, but surely there are things I can do to have a penetrative orgasm? Positions perhaps?

Does the length of an S/O’s penis have any difference?

My new S/O is 8 inches. We haven’t had sex yet, but maybe it might happen with a longer penis?