Tactics 2650 and Rapid 1100
@1
"what I can do to improve my elo" ++ Blunder checking and analysis of lost games.
"I have a rating in tactics of about +- 2650 and a rapid rating of +- 1100." ++ How much time do you spend per tactics puzzle? How much time do you think per move in a game?
"I mainly play rapid" ++ Good. 15|10 is the best for progress.
"I like to take my time to think" ++ Good.
"the best way to improve is to play rapid games" ++ Yes. Make sure to analyse your lost games.