100% understand staying put and, for sure, FD has it's pitfalls, as well. My experience just seems to have less stress and burnout with my FD peers over the PD folks that are on the other side of our building.
You guys on the blue side have a tough and (many times) thankless job, which certainly makes it tough.
As for military, you're not too old yet. I made this happen at 36 (when I started; I'm 38 now and a couple months from finishing UPT), so there's always a snowball's chance in hell. Haha. They do require the degree to become an officer/fly (potentially enlisted flying RPAs?), but it doesn't mean you couldn't head back in and be a Boom Operator/Loadmaster/Flight Engineer/etc. on the enlisted side and still be up in the air if you're not interested in completing your Bachelor's.
It would be a way to pull yourself out of the PD grind and get away from the job for a little while, put some extra coin in your pocket, and maybe add some adventure to things. You know what mil life entails since you said you were in, so maybe it's not appealing to you anymore. Haha.
But, it sounds like you're headed in a direction that'll make you happy with the CFI and working toward ATP route! Best of luck!