Grant you, this probably sounds like indecision, but for me it is an accomplishment.
I took a deep breath and told my advisors that I will not be pursuing the thesis that they had signed off on back in April. I need to work on something meaningful to me, not just to my advisors. No wonder I felt like I was on the wrong track.
Getting back to the research I want to do will likely require new advisors, perhaps a whole new faculty. But it will be worth it if I can find a good fit.
I've been ruminating on this decision for months (anxiety, anyone?). But now, I'm going to do my best to relax and enjoy the rest of the summer without thinking about my future.