Hi there. Well, it is hard to say and is most likely a combination of both. If you don't eat right and you don't exercise, it is pretty likely you are carrying around extra fat and the midsection is where that shows for lots of people. But we all get a little bloating here and there. Bloating, however, does not look like rolls. Maybe start an exercise program (can talk to your doctor about that) and a healthier diet and see if that helps. good luck
Your period will come really when it feels like it. Especially if you are normally irregular. Make sure you start healthier eating habits, drinking more water and getting exercise. Also, you're stress is probably playing a big role when it comes to your period. Try to stay positive and doing things that keep your mind off of what's bothering you.
If its hard for you to stop junk food right away, just start slow. Say if you eat two bowls of chips, cut it down to one and go from there. Start the exercising slowly too. Used to not working out at all? Take yourself a little walk. Bring your headphones, talk to someone on the phone while walking to help you keep going.
Maybe get some motivation.. I look on pinterest to find some really good workout routines, motivational quotes and pictures to get me moving. Sometimes finding that good friend that eats healthy and looks good, is the person to be around. They will just motivate you to do as good or even better than them. It will help you strive. Sometimes it just takes the littlest amount of energy to completely break that barrier of laziness.
Hopefully I helped you a little bit. & Good Luck to you!!