don't worry this is completly normal (some times). like when adults get married they some times change alot of their habbits and well some also get over weight. i know that u aren't a adult, but you did change your habbits clearly. try to change them back or somthing. drinking pop isn't that bad (i do it all the time) but try diet? or pepsi one? some thing with less colories. just fill up your house with healthy food and no sweets or junk. you will get use to it again and hopefully get back into your own habbit again of eating healhty and stuff. and also join some sports or somthing