Agreed. Blaming how big your thighs are on your gym teacher sounds lame. Honestly, the picture being painted is that you went to the gym what, 4 days a week? And only did squats? For how many years did this go on? You didn't train any other body part for how long? 21" quads are about the size of legs on people WHO DON'T LIFT WEIGHTS. Why would anyone want small legs to that degree? Why even train?
My belief? You didn't train anywhere near enough to account for "huge legs" and much of that is body fat. I would also guess that you concepts of weight training are skewed and as such, you should probably spend more time reading this site and expanding your base of knowledge. I don't know anyone in the weight room daily who is trying really really hard just to get 21" quads.