Yellow Teeth?

For years my teeth have been yellow. My mom gets kinda annoyed when I bring up how long its been since I went to the dentist, but anyway my biggest problem is that I brush my teeth when I wake up AND bedkre i got to sleep. And I don't mean a little petty brush n spit, I mean I put time in (mostly because I leave the bathroom and watch tv or something). I've tried different kinds of tooth paste. I don't even drink coffee as regularly as i used to, now its maybe once every few months if that often. Sometimes I smile with my teeth and immediately want to hide it. I made a video with my friends and had gotten close to the camera with my mouth and had to delete it because I was embarrassed like, as a little kid I used to skip brushing because...I was a kid and either forgot or didn't want to but what can I do now?