This may be counter-intuitive, but I think your focus on rank is interfering with your progress. There is no shortcut for improvement, and if you get frustrated by how long it's taking you to rank up, that frustration will negatively affect your play. Consider Ryan Li's recent win over Chen Yaoye. If you read the interview with Li (
https://www.reddit.com/r/baduk/comments/6imxf4/ryans_interview/), you'll see that he did so well against a top pro because he had already made it further than expected and was very relaxed. He didn't "need" to win to satisfy his own expectations for himself. Consequently, he scored a stunning upset.
My recommendation would be to set aside the goal of winning each game you play, and instead set as your goal to simply learn something new from each game, win or lose. This means reviewing afterwards to study sequences that you were doubtful about and explore variations, or ask someone to review with you.
Things not to do: don't play 20 games in two days (play one or two serious games a day at most), and don't accept teaching games from someone who just takes the opportunity to insult and belittle you. Sounds like someone who is insecure and can only feel good about himself by mocking others.
I think you will not only improve much faster, but sleep better as well, with a different attitude.
PS FYI - It may help to know that most people are at least two stones weaker on OGS than on KGS. KGS 4k will be around 6-7k OGS.