I'm married 14 years, had a few GFs before that too. You know what? My first girlfriend would probably have been the right one for me - I still miss her... You may be affected by peer-pressure, personal "wants" or even the media. However, the point of finding a partner is very much like you describe her. There's no reason to go looking for someone else and spend a few decades with hit or miss relationships, lots of headaches, and all that. If she feels like a good partner now, keep it up! Do not throw away what you have for fantasy or unknowns. In fact, you may never find someone out there.

Someone close to me once said "people come into your life for a reason - and they leave for a reason". Give it some time and enjoy your time together. And remember, hot girls also have a ton of guys going after them - and they end up straying away from you. Your fantasy girl will surely be the same fantasy girl for dozens of other guys. And, a rule a guy I know is "it's all about the enthusiasm". Looks or not, it's all about the relationship and your chemistry rather than looks.