Why am I so full is the diet working?

So in the couple of weeks I've dramatically changed my diet, and started exercising more. Sadly I figured that I cannot run in the morning because of the weather where I live, (above 100 degrees) So I've started swimming for a couple of hours, and doing sit ups, donkey kicks, lunges, and more sit-ups without using my arms, I started out doing 50 sets of each, and everyday I add 25. Today I will do 100. This is what my diet is like, today i had 2 sandwiches, 1 hot dog, (not the one with calories in them, just ketchup mayo and mustard) Oh and I had a peach, I try to drink lots of water and orange juice. I am sooooooo full, WHY? I barely ate anything.. Is there something i did wrong, and no my body won't go in starvation mode because I had that throughout the day. Should i do I want to make my waist smaller and get rid 100% of my belly fat Thanks (: my legs are toned and the only thing that bothers me about my body is my stomach..