Hi and welcome,
Cereal for breakfast is kinda setting yourself up for failure right from the start. You're just giving yourself a big blast of carbs and lactose, spiking your insulin. Try eating at least 20 grams of protein for breakfast instead, it makes a big difference. Whether it's eggs or lean meat it really doesn't matter, but you need the protein to start the day. I have oatmeal too (1/2 cup 5 min oats with a few raw almonds)), but even that might be too much if you are really carb intolerant.
It is actually very easy to eat well on low funds if you cook from scratch. Generally, if you use whole foods, it is cheaper, and healthier than packaged garbage.
buy your meat on sale, as lean as you can get it- but chicken legs are cheap when you buy in bulk. Also stewing beef. If canned chickpeas/lentils/beans are too expensive, buy them dried.
I eat pretty cheaply with staples such as eggs, oatmeal, leftover chicken, spinach or broccoli and brown rice for lunch, and chicken legs/stewing beef with sweet potatoes and vegetables for dinner.
Consider actually measuring/weighing your food and using an online food diary such as fitday.com- it's free and easy to use.
McDonalds is expensive for the zero nutrition you get out of it
I think you may want to stop taking fat burners as well, they are just more chemicals your body has to sift through to gain a healthy equilibrium.
Just my two cents.