arent i supposed to feel it in my stomach?
Sounds like you aren't doing them correctly. You are supposed to feel it in your stomach. I had this problem a while back, it was because I was trying hard to keep my legs on the ground from lifting off.
you are probaly not doing it right. If you have a partner or some one u know that has time, let them hold your feet in place. You will now feel it in the stomach.
You should put your feet under something like a couch so that you aren't using your energy to keep your legs and feet on the ground.