I like the buzz cut, it sucks that your hair took a hit like that though. But I would just keep it buzzed and not worry about it anymore.
Sure if I had the choice to keep my hair, or lose it I would go for the first obv, but even if you get some regrowth you will still be bald. Is that worth all the possible side effects (and the costs?).
I still have all my hair (little thinning on the top, but not noticeable to anyone else it seems), and that's why I'm on propecia (haven't noticed anything as of yet though). As soon as my crown is going bald, or you can clearly see I'm balding, I'm pulling out the razor without a guard though. See me and you are lucky enough to have a perfectly round head, just in case we happen to lose our hair.
This ofcourse is my opinion, there are others who would kill for just a couple of hairs on their head, so they can ' cover ' it up with a combover. That is just not me though. Anyways if you do decide to go with the big 3, then GL!