I think a lot of it depends on how much time, effort, and patience you have.
Not feeding them would take care of the problem within a few weeks (they'll come around hoping for quite a while), but I'd have a really hard time doing that, and it sounds like you would too. Animal control could set traps, but you know what the outcome will be.
I'd opt for TNR, as you have so far. It's great that you've already been willing and able to get 8 of them fixed. But even if only 1 of the others is a female, which is unlikely, that's still potentially a LOT of kittens in one year. I would definitely ask every shelter in your area for help with trapping and neutering the others. At the very least, they might lend you traps.
If shelters are overwhelmed, I'd try finding like-minded people. You could put flyers up at pet stores, and vet clinics if they'll allow it, asking for people interested in helping you. I think I'd be likely to respond to a request for help by an individual whereas I might not volunteer for a rescue group. I don't know why - maybe because I sympathize with your position? But I'll bet there are many others like me.
If you're not familiar with nextdoor.com, that's something you could try. There is a section where people can post pics of their pets, and at least in my neighborhood, there are several people who are clearly cat lovers. I'd feel very comfortable posting there asking for help - there are always people posting alerts about lost dogs and cats, and concerned responses from neighbors.
I hope others have suggestions for you as well!