Losing the motivation to continue reselling

I sell on eBay and facebook marketplace. I've been doing it for 4 years now. At first it was easy to stay motivated, every sale would motivate me to list more and go out sourcing for more inventory. But I have hit a ceiling. I'm struggling to grow my eBay business past $1200/month. I have been at this level for a year despite increasing my average sale price and selling in more categories. I'm just really bummed about it because I have been really focused on trying to grow the business and it's just not happening. I really want this to become a part time business that generates at least $3000/month. But it feels like a pipe dream at this point. Idk why I made this post, just venting I guess. I really really need this to work, I have schizophrenia and working from home really works for me as I would struggle in a typical work environment.