I think it was harder to adjust to going dairy-free than it was to go gluten-free. I couldn't hide the flavor of unusual flours with cheese anymore! We tried soy cheese but it was made with casein and so it still was no good (I didn't know my son also had soy intolerance at the time). You have to be careful looking for dairy replacements because some things still use milk. A friend of mine whose child has a milk allergy says that even "milk-free" acidophilus still has traces of milk because it has to be cultured with milk. I wanted so bad to give it to Barrett to help with digestion but he could not tolerate the milk-free tablets, like she said (although they may possibly contain soy so it's possible that it is the soy and not milk that bothered him).
There are a few kinds of dairy-free margarine. Nucoa, Blue Bonnet Light, and Earth Balance are all dairy-free. If you are intolerant to casein other kinds might be okay too because they contain milk but it is whey and not casein. ((Milk is usually divided into two parts--curds (casein) and whey (not a protein). Cottage cheese it the curds and so is basically pure casein. Don't ever feed it to your kid)! I found it safest to just avoid milk altogether though to avoid cross-contamination. I would also avoid using butter-flavored Crisco because while they claim it contains no milk it is derived originally from milk.
A good alternative to milk, if your child can tolerate soy, is Silk Very Vanilla which is specially fortified for kids. I found it to have the most vitamins as well as calories and my son loved it (until we found soy was bad for him). Even the Silk Plain tasted good to me. There are many brands of soy milk and you can try as many as you like, but I never found one that was fortified as well as the Silk Very Vanilla. If soy is also a problem or if you want fewer calories I would recommend almond milk or rice milk. Hemp milk is supposed to be the most nutritious, but let's be honest--it's nasty! And do not use oat milk because it contains gluten. Also, if you buy rice milk be careful if you buy Rice Dream because some of it is made from barley which contains gluten. For a list of gluten-free rice dream products click here.
You can make a very good pumpkin pie with soy milk (don't use vanilla flavored milk though). You can substitute soy milk for evaporated milk and it will still taste good (use the recipe on the package of Libby's Pumpkin), it just won't set up quite as well. You can, however, make your own evaporated milk by boiling 2 1/2 cups of soy milk down to 1 cup and using that. I could not taste the difference between my dairy and my soy pies. You can use a gluten-free crust (I'll post a recipe later), or I like to just pour the mix into cupcake wrappers and have crust-free pies. That's what I did for Barrett's second birthday. It makes for nice easy servings and easy storage.
You can get dairy-free chocolate chips as well. Tropical Source is the only brand I have been able to find. Be careful if you are sensitive to soy. They have soy lecithin in them. It shouldn't bother most people but if you are extra sensitive to soy it may bother you.
You can also buy soy ice cream and yogurt but I have never tried them so I don't know if they are any good. I have recipes though and I will post those later as well.