Hi Bella,
I'm not telling you this to put you off from taking Zyprexa, since we all have a different body chemistry, but I gained a substantial amount of weight on it, and I have never had a weight problem before. I've lost it but I'm not taking the Zyprexa anymore, and haven't for quite some time. I usually don't tell people that but since you mentioned that you're stomach feels larger - that was the first place I noticed the weight gain then I started to notice I was bloated in my face, hands, feet and ankles.
You might ask your doctor if he/she could prescribe a diuretic, or if it would be safe to get some Hydrangea (natural diuretic), from the health food store....the main concern being, that you don't take something that would go against the meds you're already on.
If your doc does okay a diuretic, and you decide to stay on the Zyprexa, be sure to eat lots of foods rich in potassium,(apricots, bananas, potatoes, etc), since the diuretic will deplete your body of it, and drink LOTS of water.
Best of luck to you and hope to hear good news from you soon.
With Kindness,
Bev