I'm in a similar situation, my rating has plateaued on 1800-1850 but reaching the "next level" seems awfully difficult.
1. Whom to play?
I noticed that you've got currently only 4/21 games against people with higher rating, you should consider playing more against 1800-2000 rated people. After joining a few clans my inbox has been filled with games where the opponent and myself are very closely matched.
- You learn more from these games as mistakes are more often punished.
- You have to put some effort in order to win, against lower rated players one tends to take it easy. Unfortunately to get better in chess you need to practice your analytical & calculation skills.
2. How many games?
Playing against good players consumes more time so 15-30 concurrent games is probably enough. After all, the process of getting better should be fun, not stressing.
3. No more stupid mistakes
Personally I still lose games to blunders, basic one move tactics that I just didn't consider. Goes to show that playing good players teaches you to be more carefull and analyse better...
4. Study material
OK, some things are easier to read from a book than learn from your own games.
Openings
Good thing about CC is that one learns the openings better. I'd suggest using some database program to study old master games with similar variations you are playing. If you feel like buying some opening specific book it is up to you.
Middlegame
Sillman's Reassess your chess is a good book but if you like wordy one try Simple Chess by M. Stean.
Tactics
Lots of possibilities. CT-Art 3.0 comes to mind.
Endgame
I don't know what is wrong with the book you already have but if you like Dvoretsky and want the ultimate endgame book try Dvoretsky's Endgame Manual (seriously difficult).
Regards,
- bahus