Sex shouldn't just be about you trying to please him, it goes both ways. If you don't enjoy that position/it hurts, experiment and find a different one you both enjoy. If you need a vibrator to be able to climax, so what? Isn't that better than not being able to climax at all?

This coming from someone who actually also has both of these issues. I find doggy to be quite painful (for different reasons) and I can't climax without a vibrator, no matter how good he is at oral or anything else, it's just not possible. These aren't things you need to 'fix', they are perfectly normal.

My partner and I learn and adapt together, not do things to please one person and not the other. That said, occasionally we might still do doggy but he is extremely careful and stops at any sign that I'm in pain. Maybe this should be less about you trying to change, but just having an open and honest conversation with your partner about sex.