It's huge. It makes me want to cry... I'm losing weight. But it's like most of my weight is there. I'm 19 and never been pregnant. So I am very embarrassed. When I wear jeans I have a bulge. When I wear underwear (pretty much always) it rolls down. Is this normal normal before ever being pregnant? Is there any excirsizes I can do? Why is it I have this?

It's a fat pannus. It's a simple result of obesity and doesn't have to have anything to do with pregnancy really, though having a few kids usually results in a "pouch" left behind. It can be removed, post weight loss, via a panniculectomy. Once it's there, the skin is usually damaged/stretched enough that it will not ever go away without the panniculectomy. Thousands of people have them...probably more like millions. You're not alone in having one.

thin is my destiny - try not to fixate too much on your tummy. Fat distributes where your genes tell it to. As you start losing weight, you will see your tummy getting smaller.

If you do Pilates, you can strengthen your ab muscles which may give the appearance of less fat. My two oldest kids (both super fit) have turned me on to planks. They're hard. I'm not allowed to put a link in yet, but if you google planks or watch some plank youtube videos you can see how "easy" they are. And Planks really are easy - it's keeping the pose that's hard!

This^

Also, you are young, your skin is going to bounce back a lot better now than 10-20 years from now. Focus on getting your diet under control to take off the extra pounds and start doing some core strengthening and cardio to help build muscle. One the fat starts coming off, you will start seeing that muscle, and hopefully your skin will (at least in part) tighten up.

I had a baby and gained 60+ lbs, and definitely have an apron (doesn't help that I had a C-section so the "apron line" is VERY defined), the more I lose, the less noticeable it is. It may never go away fully, but my skin has definitely tightened up some and I figure the sooner I get my weight in check and build that muscle, the better chance that my relative youth (I'm 26) will help my skin tighten up.