Am I Not Healthy Already!?

I have almost the exact same problem, I'm 15 and a boy , the best exercise for burning fat is cardiovascular , long distance running , biking etc , focusing on one muscle and doing short reps only gains muscle , if you work on cardio , it's great for your heart and burns fat hope this helps and good luck trying to get healthy ❤️

It's really good you sleep well. That's very helpful when it comes to hunger.

As you said, your body has learned that it needs to store fat in order to stay stable. This means it's gone into preservation mode, which actually slows the metabolism. The less fat the body has, the harder it's going to hang on, making it harder to lose. Especially if you're also low on other things like protein. Eating a lot at once at a fast pace is also known to give the digestive system a hard time distributing where the contents should go, causing more of it to become fat.

Cardio is known to be a good way to burn fat, although it won't be very helpful if the body doesn't have anything to work off of. Swimming, cycling, and running are my personal favorites. But this won't have as big an effect as eating patterns will. You're already really great about it exercising, wish I could find the urge to do that!

I've been in that situation before, and I've learned instead of eating a big meal once a day, I basically have a snack every four or so hours. It gives my body time to divide everything up. Make sure you're well-hydrated, too.

Best of luck, I'm sure you'll get back on track with your dedication!