Kim - take it easy mate, at your stage this isn't uncommon, some days things will go down and sit better than others, you cant odds it really it just happens and is something you'll learn to live with, it will get better with time and eventually you'll forget you ever went through this, at the moment your bodys learning to deal with raw food hitting your intestine and its not going to like it much, it will slowly adjust but these things take time.
As others have suggested try drinking something 10 minutes pre eating, though be careful as drinking fluids before you eat will cause your upper GI (intestine) to swell slightly and therefore you'll find you cant eat as much (this is called water loading) but at your stage its ok to eat on a wet pouch.