Feeling as though I'm getting full quicker, nausea after meals, constipation. What could it be?

I'm 17, and a male. I usually feel sick in the morning, mainly after or during breakfast, and it usually goes away a while before lunch around 12:30. Also, lately, I've been feeling full more easily than usual after a meal, and sometimes I feel a little sick too, but I don't throw up. A few days ago I did end up throwing up, but it was after working hard all day and I think I just may have been dehydrated, or food poisoning from a burger I had eaten 5-6 hours earlier. I'm very unsure and really would appreciate some help with this. Also I have been a little constipated now and then too. My BM seems to be a little more irregular than usual. Sometimes a little more than normal, usually not less. Could it be stress? Irritable Bowel Syndrome? I don't know, and I'm worried what it could be. Please help! Also: My one uncle has chrome's disease too, but I don't know if that means somehow it could be hereditary and I got it too or something. As you can tell I have a lot of symptoms, but no answers for what the source is.