Am I overweight?

I'm 13 and I weigh between 210-and 215lbs. I have strech marks on my shoulders, lower back, stomach, and boobs. My grandma complains and says I'm fat and that I eat too much, I really don't eat much (I don't starve myself) I'll eat something every 3-4 hrs I barely eat candy or chips. But my dad doesn't like to cook so we eat fast food. I drink water everyday. Should I exercise more? I feel worthless, my dad says its just extra weight from puberty.
Am I overweight?
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