dang, i didnt know you were young, lol. in your case, everything just got easier.
for eating, i would eat every 2.5-3 hours. make sure to have protein, complex carbs and some vegetables. by eating every few hours, you are elevating your metabolism which in turn, burns more calories, you have more energy and the potential to build muscle is much greater.
for me, i would burn fat by doing low intensity cardio. could be anywhere from walking at a brisk pace on threadmill, walking your dog, slow jog or slow swimming. the key is to not get your heart rate too high, but also to keep at it for a minimum of 20 mins. if i just stuck with jiu jitsu, i would burn lots of calories, but not really fat because most of the training is high intensity. like i said, everyones body will react differently.
sounds like you got the sleep down no problem.
if i was you, i would lift weights 3x's a week and do cardio 3x's a week, and on the 7th day, use that as rest.
like i said, im not a body builder or personal trainer, i just preach my experiences and what has worked for me. when i was your age, i was heavy into high school wrestling. through wrestling i was able to lose the baby fat and put a little bit of muscle on. i also learned alot about eating, lifting and training.