Hm, You are still young. It seems you like playing speed chess more than regular chess. (perhaps playing in longer games would be more helpful, especially in tournament settings). You also haven't really even done any Chess Mentor courses, and very little tactic trainer exercises.
Without knowing more than you have stated, or that shows in your profile, its going to be difficult to give you better than just general advice. Which really isn't anymore than common sense, at least in my opinion.
Reading some books could possibly help you, but if you are hanging pieces, or getting into trouble because of tactics, that might be your answer, I do not know for sure however.
Just going by the limited amount of information you have provided, its impossible for anyone to know.
Do you have friends that are higher level than you ? Are you a member of a local chess club where they have masters ?
The tournaments you play in, do you know most of the players ? ( Like local tournaments ).
The reason I am asking you these questions is because that would be the best way for you to improve your rating. Getting feed back from your higher rated friends, and opponents. (Usually right after a game is best, when its fresh in your mind). Local club masters sometimes, are willing to help younger less experienced players. I wasn't so fortunate, but you may be.
Good Luck, and I hope this was of some help, perhaps if you give the members here more info, they will be able to give you better advice as well. There's quite a few helpful people here.
It's time to learn a few openings well.