First things first. You really need to focus on getting to 540 defense so you'll no longer be crit. 20 Defense gems, or 10def/15 stam will aid you with this, other things like 16 defense to cloak enchant and 22 defense to chest enchant will help too.
Never gem for straight avoidance as you'll get more benefits from a hybrid avoidance/stam gem. For example the 16 dodge gem in your chest would be better off as 10dodge/15 stam.
As a guide I'd suggest going for straight stam in blue sockets, 10def/15stam or 20 defense in yellow and 10dodge/15stam in red. Right now it will look a bit different until you've geared up a little as the main thing you need it defense. Focus on survivability for now.
Keep running those heroics for emblems. There's a ring, neck and bracer upgrades off the top of my head for you. Along with T7 and T8 gear tokens to replace your helm/chest/legs/shoulders (which I'd aim for first and foremost). You can also run heroic Azjol-Nerub for a nice blue stam trinket from the second boss to go with your Black Heart.
Next week (assuming 3.3 goes live) you will be able to get Triumph from heroics, which means you can also get a new ring, trinket and sigil along with full T9 from emblems.
So focus on getting 540 defense, then run those heroics like never before and you should gear up fairly quickly just from emblems.