I would add some 3 drops like
Ammit Eternal or
Aethersphere Harvester, because even you have really great and aggresive start, you can deploy your entire hand in like turn 3 and if opponent deals wih it, you would start drawing 1 drops.
Ammit Eternal keeps pressure and if not dealt with, it can deal 3-5 damage each turn. I also play mono black aggro, and i's really a great deck. It's only problem is that if you can't be that fast to skip the late game, you are really in a great trouble.
Also what about
Walk the Plank? Your removal spells cannot destroy everything and creatures like ghalta are a huge problem. But this is not that important and playing with
Vicious Offering is also effective.
Good luck with testing!