stuck at 58 in hardcore on my Witch Doctor Need some advice on leveling up safely.

So I'm about 2.5 bars in to 58 and I really want to level up. I'm fairly undergeared... I heave 912 int 770 vitality and roughly 36% damage reduction.

I just beat nightmare but I am terrified to go into hell. I don't think I have the gear or the damage for it yet. I really need to level up but i barely get any exp in any acts. I've basically been kill farming zultan kulle (7.8k per kill) A grueling and slow process.

Does anyone have advice about builds and what to do going into hardcore hell like this? Will I even get experience in act 1 of hell?