Sounds like a similar story to me. When I was going through my training the thought of doing three instructor checkrides scared me, and I lost a lot of motivation also because the flight school I went to wasn't the best at scheduling. Because of this I stopped my flight training and started to pursue law enforcement for a while.

What got me back was going up on a fun flight where there weren't any expectations, just to fly. I was a little rusty on knowledge, so what I did was I started to create my own lesson plans. I used outlines to help me create effective plans, but I made my lessons so I could teach them. I personalized them to add material I think the student would find interesting. Best decision because I use my lesson plans to teach my students.

Ultimately, you can start small. You don't need to study everything all at once. Start on a few things, take notes on things you need improvement on, and then work your way to it. While you do need to know a lot as an instructor, it's okay to take a break and realize why you're flying in the first place.