That's... a good question, and I'm not sure I have an equally good answer. I'll start with your second question. Nothing I've tried has helped to the point that I've "found relief", but some things help enough that even though they don't really make me feel better, I'm even worse off without them. So, that's something at least.
I'm sure you know this, but I feel I should also mention there's more out there than just meds. There are countless types of therapy, and depending on what your issues are, treatments like ECT, TMS, and ketamine can be effective in those who don't respond to traditional medications. I've also heard of deep brain stimulation and neurofeedback but don't know nearly as much about them.
Now, what keeps me going... I guess the biggest factor is I'm not quite desperate enough that I feel I need to ctb immediately. But I don't have much hope left for recovery either. So for the time being, I'm kind of pursuing both options concurrently. I'm actively making plans to end my life, but I am still in treatment. There are some treatment options I still haven't tried and I've been exploring those. I guess the idea is that if enough time passes and still nothing has changed, I'll have my out.
Wishing you all the best in your own journey.