There's one think that slightly worries me and I'd like to ask about, because I am working on chess for almost half a year without playing any classical games (long time control). Is there any possible danger of "overtraining"? If so, how should I prevent that?
You can play classical chess online and I would recommend this to get some feedback into your play. It also will help with motivation for your training as most of us are competitive.
If you are doing lots of training sometimes you may need a break for a few days or a week periodically to enable you to come back fresh (as with any job).
I have nearly 2000 FIDE standard (I'm a rapid specialist though, 2176 national rapid). I'd like to become a FM in 2 years (I'm 17 y.o.). Unfortunately, somehow I get very tired during classical games (doctors say it's because of my visual impairment, but I don't want to accept that) and I haven't raised my FIDE rating for 2 years.
I'm currently not a PRO member, because this website focuses mainly on the openings and I would have to completely reassess my repertoire and also my playing style quite a bit. There's also another issue with the middlegame topic, that I know many of the games covered in the course with 100 games about middlegame.