I'm 5'5 and 126lbs, I have stretch marks on my legs and some people call me fat
Screw those morons because according to your BMI (21.0) you're at a healthy weight. If you are NOT healthy, then try to be. I'm not saying that you should never eat sweets (because that would make me hypocritical), and I'm not saying become obsessed with exercise. Just be reasonable and talk to your doctor.
EVIL ME: Find out those other peoples' BMIs and fight back with that (as a calm defense- do not BECOME these people)