I think your doctor is being fair actually, surgery can lead to a host of other problems, he seems cautious and what he says is normal is normal. It sounds to me like you are looking to avoid something and looking to your doctor to solve your problem.

What makes me think this are your comments "by your standards" whose?? the bdsm standards society?? also your comment "It seems silly to say, but I feel like he is just too big..." This isn't silly, and maybe your pussy is trying to tell you that. Not that sex is out of the question but I think maybe you need to take care of yourself and your body is telling you you're not doing the best job so it's protecting itself.

I know for myself when I feel like I have a physical limit of my own, I feel a sense of failure, and the head dialogue goes something like... "I should be able to ____ , other people don't have this problem why me?" I have a history of pushing myself and disregarding my body's limits, this inevitably results in injury. Maybe you have to cut down your play sessions or their intensity, but I think you will have to discuss with your partner your limits and your needs.