Two questions in one.
What you weigh is irrelevant (wihin reason)
Am I fat???
Well if you have wobbly bits and dough-balls of white pasty flesh around your hips, waist, thighs and bum then of course you are fat. That's what fat is!!!
However you can be over-weight without being fat. I am overweight on every chart you can see, but I am not fat at all. A little belly in my middle age maybe but a BMI well within safe limits.
Only you can tell if you are fat. Stand in front of mirror naked, and whilst realising very few ladies and girls have a body like a super-model (which I may say is yuk!!) do you look fat.
If you are, then I am pretty certain it may just be puppy fat which will go before you reach twenty.
But please take note. If you are only a few pounds or even a stone too heavy, at your age don't start going on silly faddish diets and puking your guts up. A little extra on a woman when she is a bit older than you is very pleasing for the vast majority of men!!!