I met my wife-to-be at 18, both freshmen in college. I went through the same thoughts at 19. These are very very common thoughts. I thought about all the other women that I knew, whether they were available to me or not. I couldn't think of anyone who even came close to meeting all the criteria that she fulfilled. We have been together almost 18 years now.
Of course, I am a "sufficer", not a "maximizer" (see the excellent book
The Paradox of Choice: Why More Is Less). My wife is at least a 9.5 on my 10 scale. It is possible that there is someone out there would redefine what a 10 is on my scale. It sounds like your girlfriend "suffices" you quite well.