My girlfriend was openly and proud about being extremely slutty.

Now I don’t think that makes her bad or shameful in anyway, that’s her life story and it made her who she is today and I love her. But it’s always eating away at the back of my mind, what if she’s super unsatisfied sexually? She’s said I’m not her best anything with sex, but says she loves me. Am I just in my own head and potentially ruining something great?