I have 5 hc lv 85 characters still going strong, and bunch of others in hc ultimate that i use from time to time.
I would say nice job for crucible devotion farming, but i would recommend you to start crucible devotion farming at lv 2, and stop it at 8th devotion points. the original guide that described this method recommended farming till 10th devotion points, but that's what i do anyways.
Bosses that may kill you in the storyline are bolvar (he got nerfed for melees so he's easier) commander lucius of fort ikon armory (that urgot looking boss who gets significantly strong for ultimate). and log, that final boss. I don't recall anyone else strong enough, really. If you die to someone else other than these guys, you might want some help.
bosses that are not necessarily part of the storyline and are not mandatory include the spined cove corrupted shrine ghost boss (he's not in ultimate since that shrines not available in ultimate) anesteria the outcast, the mad queen, avatar of mogdrogen, skeleton key dungeon final bosses, and nemesis bosses.
the real b*tches are the bosses that can lower your resistances, including anesteria, avatar of mogdrogen, etc. they are op as af; exceeding maximum resistance? doesn't matter. having increased maximum resistance? doesnt matter. they still lower your resistances and you always need to be cautious of them. scares the aff out of me still in gladiator crucibles, and u see black legion medics healing them that annoys the aff out of you but thats another story XD.
Also, what i feel about the game is that normal/veteran and elite is like tutorial for ultimate. ultimate is the real game, you really need to brace yourself if you haven't experienced it even in softcore yet.
But then, more you play, better items and more items you hoard, so it will be easier for you to play hc as you play more. I would recommend going full retaliation or sword and board build for your first hc runthrough just for the sole purpose of surviving to lv 85 and get your first legendaries/mi's other goodies that may help to increase your survivability.
BIG NONO to squishy and flashy build for first time hc.