Thanks for your opinions, SpiritoftheVictory and Till!
Learning an opening is hard and I realize there are many holes in my repertoire. I was thinking, playing games in tournaments is one of the best way to learn theory especially if you are in an unfamiliar territory because you get to think for yourself and play moves that makes the most sense to you.
and Till, I agree, that going through grandmaster games and "knowing" them helps out alot in the long run, and has gotten me wins because i "knew" the key ideas for the particular positions.
My 2 weakness right now would be converting a winning position (not a won game), and thinking of plans in the middlegame. I think the latter is curable by playing many long games but i wonder what to do to convert my advantages in the game...
Without pain, without sacrifice we would have nothing. Honestly, you should definetely play as many tournaments as possible. Don´t worry about your rating points, when you don´t risk to lose some you will never gain any. I would just do a lot of preparation for your next big tournament. First of all you go through your opening repertoire. You check out all the main lines you play, remember the most important theory lines and play through Grandmaster games in order to understand the typical plans in every opening you play. The first step for you to improve should be to get a playable position against every opponent and even win some games just because of your opening knowledge. When you know the names of your opponents before the round starts you should also research them in your database and check what they play against your openings. This will give you new stuff to prepare. The opening repertoire is the most important thing for you at the moment, but you should also do tactics every day and analyse your and strong players games. I woudnt play any more blitz or bullet games until you finish the work on your opening repertoire. Afterwards you can play a lot of 5 min games in order to see where you still lack some opening knowledge.
Ah, and from my own experience I can say you improve just by playing a lot of tournaments if(!) you also practise things I mentioned above.
Good luck!