For me the jump from ~1000 to 1400 was mainly practicing tactics, and playing slow games.
I would suggest the "Online Chess" on this site. However, I wouldn't get more than a few games going at a time so that you can really focus on deep calculation. Also, try not to use the "Analyze" or "Explore" buttons. When it's your turn to move... just stare at the board and visualize the moves in your head. That way you're not cheating yourself into a higher Elo.
You seem to enjoy live chess quite a bit, so keep doing that... but I might suggest playing longer time controls. Perhaps 15-30 min games.
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So... "Online Chess" for deep calculation. "Live Chess" for when you don't have a move ready in "Online Chess" and want something to do.
Also, I tend to study (viewing GM games, looking at my own games, practicing tactics, etc...) about 75% of the time, and play only around 25% of the time.
I'm stuck at this rating. Please, take a look at this game and tell me how I can improve!