I used to feel nausea every single day, especially when I was younger, usually when it came to going out somewhere with my mom and dad or having to eat out somewhere. And DEFINATELY used to feel full after tiny portions of food - but I think thats because when I was young I thought that if I dont eat that much, then I can't V* it up...
I was really really skinny until the age of about 12 when one day I felt soo ill I was certain it was a bug and was worrying all day and didnt eat a thing. Then at about 6pm I was sooo hungry but felt so ill I didnt know what to do - surely if i eat now I have more chance of V* - i thought.
But my mom made me some potato waffles, and as soon as I ate one i felt soo much better, and I think I ate about 6 that night! And since then I put on weight, learned to eat more (but not massive amounts still, but healthy amounts) and feel much better, and also dont feel that same ill feeling every day.
But I do feel nausea most days, mainly at night, or if im somewhere thats too warm and small. I still struggle now and again to eat normal meals, but its usually a phase that lasts a couple weeks then Im ok again for a bit. I still think about V* every single day in some way, and have done ever since I can remember, but i dont know how to change that!
My advice for the meal thing is to take your time with the meal, and try not to see it as a threat, or something that you need to eat all of, as you will get yourself in a state (which is what I used to do when my mom and dad used to tell me off for not eating enough).
If you feel full, you feel full, no big deal, and if you get hungry again later have something then.
Hope that helps