Both my kids had food allergies - I only made it nursing my son for 6 weeks. He developed colic, and reacted to everything I ate. I was so inexperienced, away (far, in Hawaii) from family support, and then found out at 8 months (he was on soy formula) that he tested positive for dairy, egg, sesame, and peanut allergy (after anaphylaxis from a teaspoon of yogurt, he could have died without the epinephrine they gave him at the base clinic).
My DD reacted to dairy in my diet, so I eliminated that, and eggs to be careful, and she weaned herself at 14 months. I got her tested at 2, and she was slightly dairy allergic, but outgrew it.
DS outgrew peanut and sesame, but still is slightly dairy allergic, and definitely egg (just retested as he reacted to his flu shot for the first time this year). He gets a blood test annually at Johns Hopkins Pediatric Allergy clinic. He was also part of their first milk allergy immunotherapy study, and is now tolerating dairy in breads.
I got some good recipes from the FAAN cookbook, but it was an old one. I don't know what they have now, but they may have a cookbook. Mainly, I like the pancake and cake recipes - and cookies too. It takes work, but we have done all our own baking for parties and birthdays. They have substitutions for you too. If you want a specific recipe, PM me and I'll get it to you.
Eating out - that was harder. Other folks (even family) didn't understand how important it was for me to keep dairy out of my diet. My family also never understood how to read labels - they used to constantly try to give my son things that he would react to (and did - one Thanksgiving, my DSIL spoonfed my then 20 month old son mashed potatoes, just one bite. I saw her do it, ran over, and she said it was just one bite. UGH.... I gave him liquid benedryl, as he was already hiving up around his mouth. Sure enough, a short time later, he projectile vomited all over). When I was in a nasty mood, and one of my in-laws would ask, "What would happen if he had some dairy?", thinking maybe he could try some, I would answer, "Well, he could DIE!". He's had anaphylaxis twice.
Just be careful, talk to the servers in restaurants. They are better now than a few years ago, I think.
I haven't had to avoid soy, but think it is a hard one. We have a local organic store chain here, Roots, and the organic places are great. They usually have allergy-free aisles, like for vegans, folks who can't tolerate gluten, and I'm sure they have soy-free things. See if your area has one of those organic market places. That really helped me - you can get rice dream ice cream treats and things. I like having sweets, and with nursing you need to eat snacks to keep up your energy.
Good luck to you!!!