Hi M.,
I have a daughter who just turned 5 months and I am glad to say that I have shed all of my pregnancy weight and would be more than happy to share some advice on some things to maybe changing your lifestyle. You may also want to check your stress levels and see if you are having any thyroid issues. In your post you stated that you are a single mother of 4 and although you may be loving it I know that it can still be stressful at times.
You may not eat fast food but you may need to look at your overall sugar intake which is most likely the culprit. I can tell you to stay away from, white bread, cookies, cupcakes, cakes, even granola bars. These things are filled with white sugar and cause you to store more fat than you desire. Contrary to what many people think stay away from margarine or imitation butter spreads. You can use butter all day to cook whatever you desire to cook. Drink plenty of water and if you may not like the way water tastes(ofcourse because there is none) then add a bit of lemon, lime, or honey. You can eat as much meat as you like as long as it does not include, pork ,shrimp, lobster and other scavengers and fish without scales(If they do not have scales then do not eat them). Take cod liver oil, sounds gross but this will help your digestive system quite a bit and aid you in your vitamins A and D intake(you might notice your skin glowing more). No more fried foods, it may sound hard but once you stop its hard to go back to deep fried anything in the beginning. Eat real fruits and vegetables nothing in a can or those sugary fruit cups with all of the syrup fresh or frozen is best.
These are just some of the basics so let us know how you are doing in about a week or so. Remember that you have to make the decision to actually follow these things and I guarantee that you will become a different person. Continue to walk everyday and keep the faith. We are cheering for you!