It's great that you're taking your poker playing more seriously and improving your game through reading books and watching streams. Your current win rate of 68bb/100 is very good for 2NL, and it's likely that you'll be able to continue making a profit at this level.
When it comes to moving up in stakes, there are a few factors to consider. Firstly, you should have a good understanding of the game at your current level and be comfortable with the strategies and tactics you're using. Additionally, you should have a solid bankroll in place to handle the increased variance that comes with higher stakes.
It's important to note that moving up in stakes too soon can be dangerous. If you're not ready for the increased competition and higher variance, you could end up losing your bankroll quickly.
In general, it's a good idea to wait until you've reached a consistent win rate at your current level before moving up. You might consider moving up in stakes when you've played a significant number of hands
, around 10,000-20,000, and have a win rate of at least 5bb/100 at your current level.
It's also worth to consider that moving up in stakes will increase the difficulty of the game and you will play against better players, so make sure you are comfortable with your game and your bankroll is healthy to handle the increased variance.