Ahh... i really need help (easy 10 points)?

You might want to go to the store and try it on in the fitting room, that way, you can be sure which one fits. If it is not available in the store, just try your best. If are still growing (like a teen) get a one, if you are sure that you can fit in a smaller size, get a 0. (Personally, I would get a 1 though). I hope this helps.