Don't beat yourself up over this. You do great work and if you enjoy it, keep doing it. I think this happens to a few hobby bakers.
I learned a lesson 2 weeks ago while I was delivering a cake to a friend of a friend. I had just finished setting up the cake and was on my way out the door when a guest at the party ambushed me rambling on about ordering a cake for this, and that, next thing I know she's in tears asking me to "donate" a cake to her uncles funeral. At this point I just wanted out of there and said "ok, but I can't do much on short notice, I'll do what I can" I don't know what he heck I was thinking, but I am always in need of practice ( and I have a hard time saying No) so I let it slide. I was hoping she'd forget about it, and never call. Ohh, she called alright, 27 times in 2 days and also started wanting to make flavor choices, and design choices. I kindly told her "this is not my full time job, I don't have much on hand, I'll do the best I can for you".
I put together what I feel was a nice "FREE" cake and delivered it to her neighbor as she requested because she would be at the funeral. 27 calls in 2 days, but couldn't make 1 call to say "Thank You".
Is it my own fault? Yes, I could have and SHOULD have said no. But I didn't. I was feeling angry , insulted and taken advantage of ,but now I've decided instead of giving up something I enjoy I am going to streamline my customers. If I get any indication that the customer is unreasonable, or just a nightmare from square one, I'm turning down the business no matter how much I like to practice. Some people are just not worth your time, save it for those who are.
Don't let 1 unreasonable person discourage you