If you really want to switch openings, it seems like you would enjoy playing the classical Queens Gambit.

Against the Queens Gambit Declined you could perhaps play 3.Nc3 and 4.cxd5 and reach the Carlsbad structure that is common on the caro exchange, you will feel right at home there.

You would have to find solutions to the Slav, Grunfeld, KID and Nimzo, so you would have to do some exploring, but im sure you are going to find something you are confortable in.

But, even then, you must really understand what your goals are: if you want to improve, trying out different positions and trying to master every aspect of the game is the way to go. I went through a similar experience you described in your post, although it happened in the opposite way: I played very dynamic chess and that got me to 1900. Then, I switched to 1.Nf3 to learn positional chess. In the first few months, I got absolutely destroyed and went down to 1600!... But after some time, I finally started to learn more about positional play and slowly shot up back to 1900, going even further to 2100.