You know, I know it isn't a popular opinion, but sometimes you're just not size compatible with someone.

Had a large ex, we did the whole 9 yards... foreplay, lube, specialty condoms, birth control and no condoms, sex toys to help prep/ stretch, trip to the GYN. Ultimately, there were only certain times of the month where penetration was possible without bleeding and there was always some pain. Tried anal did NOT go well, ended up with tears that still reopen YEARS later whenever I'm slightly constipated and straining.

Ultimately humans come in sizes and some fit together better.

The sex difficulties made us both grumpy because we were aroused and attracted to each other but it hurt and was such a production that we had sex less and less. Things fizzled, life moved on and I now know my size limits better and like having sex early on in the relationship so if someone really won't be size compatible we find out before we get too attached.

I really DO hope you find a way, but if you don't please don't beat yourself up. I know it can be heartbreaking and really suck, but size is just as valid an incompatibility as anything else.