My bf’s penis is around 4” and I am on the thicker side and I want to know what are some good positions?

We currently do missionary, cowgirl, 69, and have recently have tried -Doggy -Spooning But it seemed like we just couldn’t quite get the angle right and I think it was a mix of he wasn’t quite long enough (which is what he said) but I also think my body shape didn’t help. He got it in during doggy at one point but it kept coming out and was difficult to get back in. I was very arched for it as well. I was wondering both what are some other positions we could try, if there’s ways that we could have better luck with those positions we did try (like if using a pillow somehow could help or any way I should try flexing/stretching my body to make it easier for him