P., we live in a 30 year old house as well and were absolutely invaded when we moved in two years ago. It was really horrible, like something out of a Sci-Fi movie. First thing was I just finally had to break down and call a professional. We now have someone come out and spray quarterly for a little over 80 dollars each time with a full warranty in between visits. It's more than I wanted to pay, but I came to the conclusion that this just needed to be a priority, and the bugs can just be really bad in the South. They only sprayed the interior of the house the first time and dusted the inside of the plumbing, then they spray exterior only on other visits. If you have a newborn and the problem is the kitchen, you can just ask that they spray the kitchen and dust the plumbing in the kitchen for now. (We use All Pest Solutions, think they are in Wylie, they are a very child-pet friendly company). Ammonia is probably even way more toxic than the chemical they would use.
Secondly my husband and I got "Great Stuff" a spray foam sealant from Home Depot. When we got on our hands and knees we discovered an open seam under the cabinets that was not visible, where bugs were coming through. We sealed all of those, every open crack, and then under the sink all around the plumbing and tubing. Then I got some thick round foam tubing in the weatherstripping section of HD and stuffed that back in and all around our dishwasher, filling all of that open space where bugs could come through. It expands to feel the area. (Not visible from the outside) After this we were very vigilant about crumbs, dishes in the sink, etc. for about two months. Haven't had any problems since! Don't get overwhelmed, you can fix this and have your nice house back! Message me if you have any questions.