I like your posted build, and think it is running in the right direction. I would recommend a few things to tweek it into the right direction. Hope this helps you!
The biggest thing for you is I would commit to a damage type. Sadly thieves are not the best to split build with. We do okay rounded out with stats, runes, and sigils, but we are not rewarded as nearly as much as Necromancer, Guardians, or Elementalists.
Your build seems to be going into some power traits on your weapons and armor. You have +728 into power combined in all your pieces. I like the thought of splitting for runes in bleeding, and think you should commit to doing a solid bleed condition build. If you do that, I would recommend dropping carrion completely from your build.
When you drop Carrion, you have 3 ways you can roll. You can go more traditional and standard for the Rabid, or you can do a blend or Rabid and Carrion. The last is going the super tanky condition path of Apothecary (I call my build the witch doctor, and it uses the Apothecary set). If you go Rabid or Apothecary, grab some Runes of the Undead, as they are a backbone of the build in my opinion.
For thieves, since we are so poor at condition stacking with basic skills, we need to overcome this by either stacking more condition application options, or stacking more condition duration. In regards to the above applications, we have a few choices that really do help and give us a fighting chance against high removal classes—venoms, sigils, and at least 20 in deadly arts. Sadly as a class, thief does not benefit from condition duration in Sigils—our stacks are removed to quickly for how few we put on. Instead I would focus on keeping food buffs up and running +40% condition duration, as well as the X% you get from how ever much you put in Deadly Arts.
I would recommend dropping Acrobatics and adding it to either Deadly Arts to gain Mug (one of my favorite traits for thief!), or adding it to trickery to gain more condition damage and buffs from stealing.
Now from here, we go to weapons. Get some on-crit or swap Sigils for your weapons. I recommend going Sigil of Earth if you use Rabid weapons and the V trait from Trickery. With about +45% of crit chance, you will see stacks going up rather quickly (2 second cooldown for the Sigil). I enjoy using Sigil of Doom as well. The free poison proc is never a bad thing—it stacks nicely!
The would highly recommend going trait II in Trickery as well. This will help compensate for your low health. It helps against zerk classes, and does give you a slight edge in getting out alive.
Lastly, drop Shadow Signet. Run NOTHING on your bar that shows you are a thief. I know it sounds stupid, but not knowing what class you are in WvW helps a ton. If you have a Signet or buff that spoils your surprise before the fight even starts… you will have a tough time winning fight. If you play chaotic condition thief using C/D > Unload > Shadow Strike > AA until C/D is up or stealth is ready—people have a tough time sticking to you, you can evade, and your conditions are doing damage (a lot).
Also, look into Skale Venom and Spider Venom. They are better than you think!
Keep your Refuge or Shadowstep… but not both. Not if you trait into II in Trickery and stack some regen/healing power.
Hope that helps! Good luck! If you need any more help just PM me or find me in game.
-Icarus
