I havent gotten my period for 2 months?

Ok, you're 5ft 8 inches and 108 lbs? Your BMI is 16.4 which is underweight. That's exactly why you're not having your period. Your age isn't a big deal, some women have a period as young as 9 or 10 nowadays. Going on a crash diet is not healthy and that's why you are not bleeding. Edometrium building up is not going to cause your belly to pooch. What you're eating may be putting the weight in one area or you may have a gastrointestinal issue, or it could be a m on one of the organs in that area growing. When you get your cycle, if the egg is not fertilized, it drops into your uterus and the lining of your uterus sheds and thats what you bleed. Your body basically builds that lining all month long until you ovulate and then it sheds when pregnancy doesn't occur. Again, the belly protrusion probably needs checked though.