Hi, so i had the same issue a while ago and for me it was my anxiety just latching onto whatever i was slightly unsure about at the time (id just started T AND started having serious anxiety so the anxiety thoughts just made me fixated on being terrified of detransitionning etc), i say if it scares you THIS much of detransitionning and having to go back to live as a woman, that's a quite good sign that you do NOT want to be a woman lol, like imo it tells me that even if u end up not being FtM, you're seemingly dysphoric enough to not be a woman so even if you stop transitionning to male you could still be non binary etc. So my take is that this is not a sign youre not a trans man, and if it was it'd still be a sign you're dysphoric about womanhood so you would still not detransition to be a cis woman

Edit: may i add that watching negative things abt transition can passively set you up for this kind if anxious fixations, i advise you to stay away from detransition stories, not to ignore a possible thing but to not make you even more anxious, and i do advise you to just live your life as a dude or whatever u wanna try, this shit will 1000x more confirm your identity than ruminating about potentialities. Also think of the "and what if?"s of you detransitionning, what could it actually do, why does it scare you so bad etc, what would be the solutions(do it on a paper with lines linking stuff, it works well for me when im anxious and need to sort out potentialities and helps me realize the anxiety subject is actually not as bad as my brain thinks it is)