Appreciate any experience you care to share!
I'm replying to this rather late...I'm curious to hear what you ended up doing.
I've done TMS a number of times. If this is the first time you've done a course of it, I'd strongly recommend you finish it out. I'm guessing you're in the US based on your description of the protocol...For some people, it really is a near-permanent fix. For others, a significant and meaningful long-lasting improvement. For some (people like me), there's an improvement that eventually fades, so I go in and do it again.
Bear in mind that it's effectiveness and longevity are impacted by how you use your brain during the 6-week treatment window. You should be pretty actively participating in some form of cognitive therapy, specifically making sure that you're working on changing some of your more harmful core beliefs.
Also - you can assume that the TMS is still moving towards maximum effect for another six months, following treatment. That's how long they've observed regular change continuing in the mood areas of the brain.
Ketamine isn't going anywhere. I've done Ketamine via nasal spray, not via infusion. Again, not knowing where you are, it's hard to say - in my neck of the woods, infusion therapy with ketamine isn't covered by most major insurance plans, and isn't cheap. BUT it's rapidly gaining popularity, and may become more insurable as a time goes by.
My personal advice would be to continue with the TMS, finish it out. Then see where you're at. If you experience a positive result, talk with your doc about low-dose lithium, which is (apparently) very beneficial for extending TMS results.