Your situation is fascinating, and I completely get why you're on the fence even though you're not happy in your job. I quit my similar and also high-paying biglaw job a year ago to travel around the country with my husband and toddler. While we're on our way to being FI, we do not have the stash built up that you do and weren't just a year or two away. Had we been, I would have stuck it out and gotten to FI before quitting. Funnily enough, the only place we visited on the entire trip where I had an "ah-ha" moment and felt like it could definitely be home was Bozeman. Strange... And the weather is exactly what we were looking for - to other folks in the forum, some people actually prefer winter! Anyways, for other reasons (namely family ties), we're most likely not going to wind up there, but just thought I'd throw that other similarity out there.
As for what I'd do if I was in your situation, I'd scrap any artificial deadlines you're giving yourself and instead take the time that many folks have suggested to get your ducks in a row and really figure out your next steps. If you get to a point this summer where the job is giving you so much anxiety or stress, then know that you can quit at any time and be perfectly okay. As for the worry about quitting and not being able to get a similarly high paying job again, I completely get it. That was my biggest hold back, as well. Sure, you know you could get another high paying job, but it might not be quite as high if you get off the track for too long or, if you did, it would likely be filled with the same negatives of your current job. That being said, given your stash, you could take a low paying job that you really liked if you felt like you needed the extra cash. So, I'd say to just spend the time really getting yourself comfortable with the numbers and figuring out your next steps. If you believe that you're already there with the numbers - as in you'd be able to support yourselves at the lifestyles you'd like to live off of your passive income, then don't stress at all. If not, then I'd do some serious work to figure out what that number is and what the lifestyle is. Working another year may get you there, but so may only work six months. Or, if you have your hopes set on a more lavish lifestyle (and I'm thinking you don't), then figure out what exactly would get you there without worrying about how it fits in to the various compensation schemes at your current place of work. Once you've figured that out completely separate from your current job (and all the emotions that entails), then you can make a much more accurate assessment of whether you're ready to call it quits this May or at some later date in the future.
You're not alone! I'd love to hear what you end up deciding to do. And if you do move to Bozeman and by chance we wind up there, too, let's grab a beer.