I'm 5'5". I see plenty of guys when I'm out and about who are around my height. It's pretty common for us to stress out about passing when we're short or have small hands/feet (and the reverse for the ladies), but I really believe very few people will notice unless you say something about it.
I've never had any negative comments about my height, and only a few about how small my hands are, but that's only because I've gotten fingerprinted for work purposes multiple times since transitioning. I think it's natural to have concern about these things, but important to realize that aside from yourself, it would be very rare for someone to notice and connect the dots.
As far as the online bullying, report whoever is doing it on whatever platform it is (Facebook, Instagram, etc.). I know Facebook at least you can report people for harassment and I think online bullying is in the same report line. Not sure about anywhere else.