I feel like I'm at a point where I have to choose between her or having good sex in my life. I don't think I'd find another woman I'm as comfortable with.. but I also don't think I'll ever have a great sex life with her.
You are correct. If you really need good sex, you aren't getting it from her. I don't know your age, but I find younger girls, like in their 20s, 30s sometimes, are generally bad in bed. They are whiny, insecure and uncreative. There are exceptions but those exceptional girls got married long ago.
While girls in their 40s might have gained a few pounds, they are often very sexual, sometimes multi-orgasmic, and very expressive. And worth it.
I have a long time interest in psychology, specializing in relationship dynamics for 30 years.
(Please note, we give the best advice we can based on the information given in a post. For better advice, please include the age of all romantic partners.)