S.,
My son is intolerant to both dairy and soy. The proteins are really similar and most babies that can't tolerate one are likely to not tolerate the other. You might want to try a hypoallergenic formula instead. If I were you, I'd ask for a referral to a pediatric GI doctor. My son also has reflux and he's on Prevacid. We started with Zantac and that didn't work for him at all.
The basic rule with starting cereal is 4-6 months and with preemies I believe you have to adjust their age according to their due date. If they were 2 months early, you'd start cereal when they are 6-8 months old. You can find info on the "signs" a baby is ready for solids on any of the baby web sites like www.babycenter.com. But if your pediatrician says they aren't ready, they aren't ready.
:-)T.