Im Trying to lose some belly fat?

Im also seventeen in the same situation except im a female. It's fine that you are doing cardio but that is only to maintain you heart healthy not necessaryly to loose weight. What i was told by a trainer is that in order to loose weight you first need to add on punds of MUSCLE. for every pound of muscle u loose a good sum of calories ( dont memeber the exact amount so dont wanna give false info). So you need to start lifting weights and such to gain that muscle which is what ultimately burns the fat. Plus it's only beed eleven days.. it takes the average human a month to gain a pound of pure muscle. :) ... Keep at it soon u will see the difference. Good luck