does your wife display any other behaviors that seem slightly "off?" it does not need to be this flagrant, or this terrible, but something you may have passed off as a harmless quirk?
i went undiagnosed with OCD for many, many years because most of the things i did were invisible to others. i had a whole host of compulsions regarding sicknesses that no one but me ever saw.
the things that people COULD notice--my compulsive hand-washing, for instance--were easy enough to write off. all i had to say was "oh, i just like to keep my hands clean!" and honestly--who is going to argue with that? people don't find it that weird that you're a germophobe.
another example--i'd often stay up most of the night checking and rechecking all the locks in my house. in the morning, if someone asked me why they could hear me up so late, it was easy enough to say--"just couldn't sleep!" the behaviors i couldn't hide, i found ways to excuse, and people were able to accept them as little eccentricities.
when i first got into therapy, my therapist had me read a book about OCD to better understand it all, and i was surprised to learn that, like me, many people were adept at hiding their symptoms from their loved ones. the frustrating thing about OCD (for a lot of people, at least) is that YOU ABSOLUTELY KNOW you are being weird, that your actions are abnormal, and that other people don't have to live like this--but you can't stop. there's a lot of shame, so you learn to hide as many of the compulsions as you can. there are a million plausible "quirks" to latch onto, and it's easy enough for people to rationalize your behaviors if you have a good excuse.
i don't know your wife, and i don't know if she has OCD. there are plenty of people who are just neat freaks, so it's kind of impossible to say. but "oh your job is just transporting boo boos!" could easily be a cover for "i literally cannot stop doing what i'm doing and it's easier to make you think i don't value your job than it is to tell you about this crazy thing i'm doing."
i would maybe pick up a book on OCD, or do some internet research on spouses of people with OCD, and see if any of it rings true. if it does, you might have to have a really serious talk with her.
if it doesn't ring true, then ... you still need to have a serious talk, i guess. haha. i would ask her to go to couple's counseling, and then specifically bring up the things she says about your volunteer emt position with the counselor. whether she has OCD or not, what she's saying makes this definitely sound like a deeper issue. if she's not getting it through a normal conversation about your feelings, and if you're very committed to her, then you have to find another way to get through to her.
in the meantime--have you considered moving your boots to a spot that she wouldn't think to check? like, under your bed, pushed back against the wall where she might not see? maybe move them while she's out grocery shopping, or after she falls asleep? the onus shouldn't have to be on you, but until you get through to her, it sounds like it might be.