It seems to me like you're rushing and expecting to become good too fast, it takes time to get better. I could be wrong about that statement, so don't go crazy on me for making it. =P
Go save you're replays and watch them and look for exactly what you're doing wrong. Are you dropping your combos? If so, go into practice mode and work on your executions. Another problem a lot of players have is that they auto-pilot. Meaning they just mindlessly go in a game and just start doing combos without a true purpose. Every move you throw out should have a purpose whether it is to move them into the corner, or bait out a move. When you're in an actual match read you opponent, look for patterns, mistakes they're constantly doing, and capitalize on those mistakes they make. About your bad habits find out what they are and go hammer them out.
You may keep watching, reading, and studying videos and threads that will help you, but in the end experience is key. So just keep on playing and practicing. Don't expect an over night miracle to happen and you become good all the sudden. You will slowly improve the more time and effort you put into it. You might not see improvement right away, but in a month or so you'll see your game getting better. It also helps to have some friends to play with that can always point out errors and see if you're really improving or not.
