I have been around 1700-1900 rating (glicko 2) for a while. I have been losing on tactics when there aren't many pieces left.(mid-end game) My positional thinking is alright, and my endgame skills are alright. I play king's pawn with white and caro-cann + queen's indian for black. Also I have big strikes. On a good day I can win 5 in a row, on a bad day I lose 5 in a row. How can I improve my rating?
Do tactics regularly (possibly every day). Below 2000 rating is probably the best thing you can do, especially if you have a weak point there.
Ideally you want to practice for ~20-60 minutes (depending on how committed you want to be) on problems that do NOT give away the theme of the tactic involved (e.g. "exchange sacrifice", "overload", etc).
Another thing you can do is to review your games, and if you lose due to tactics try and figure out which was the best response to parry that blow. In any case reviewing your own games is the key to improve (first review them on your own, and once you're finished go through them with an engine).
Finally, I think you might want to watch other people playing, especially ranked 200-400 higher than you, and then review those games as well. I find it very useful because I usually understand the reasoning behind moves I didn't think about during my own games.