Emily,
My now 21 month old is allergic to both dairy and soy. When I started the elimination diet, I avoided dairy & soy (both obvious and hidden in other foods), eggs, nuts, peanuts, chocolate, fish, shellfish, citrus and tomatoes. My son improved dramatically with that so I started adding foods back one at a time and was able to add back everything but dairy, soy and eggs. I was able to add eggs back around the time he turned one. Obviously there is a learning curve to doing this type of elimination diet. Getting it started is hard but maintain it is not. You have to 1. figure out what not to eat 2. figure out what you can eat and then 3. find enough variety to keep from going insane.
What I found was the easist way to eat was to go to a mainly "whole" food diet. The closer stuff is to nature, the less chance there is something added to it that you can't eat. I ate lots of meat (mainly grilled but lots of crock pot too), beans, rice, potatoes, veggies and fruit. As an added bonus I lost 20 pounds and my cholestrol went from 294 to 204.
You can get dairy free margarine. Nucoa is dairy free (sticks, comes in a gold box) and one of the smart balance margarines (I think it is the one in the green tub but I don't remember for sure - I use nucoa) is dairy free. Olive oil is also a good substitute for butter depending on what you are using it on. I don't use cream so I can't help you there but you can bake with rice milk in any recipe that calls for regular milk. It turns out fine. And that includes pancakes. Eggs are a little harder. You can google egg substitues and there are equivalents you can use. I've tried several and they don't work so hot for baking so I tried to only bake with recipes that don't call for eggs. You can also get an egg substitute at natural markets (it is called something like "Ener-G" and I think it works okay but not fabulous).
You basically have to read the labels on everything you eat. If you don't know what is in it, you don't eat it. Personally I didn't want to eat anything bad enough to watch my baby scream in pain so to me it was worth the "sacrifice" to have a healthy baby.
Oh, and start looking for recipes that naturally don't have the foods you are avoiding in them and learn to cook with more herbs and spices. I found that once I eliminated dairy and soy and therefore most of the "fat" in my diet that my diet was really bland and that got old. So by using more herbs and spices and getting more flavor, I was able to enjoy my food more.
Basically, if your baby is sensitive to dairy the only solutions are to either avoid it or to stop breastfeeding and go to a hypoallergenic formula.
I was dairy and soy free for 18 months and I lived through it. My son is 21 months now and he's still dairy and soy free. So the practice I had cooking for myself has really helped me in making sure he has a good and varied diet.
I've obviously got a lot of experience with this so if you want to talk more about the specifics of how I did it, what I ate and all that my email address is teralee999 at hotmail dot com.
It really is very intimidating to get started but it gets much easier.
:-)T.