Need Help Building Crit Hexblast Witch

Hey guys! This is my first post on these forums, and I had a question.
I'm playing a witch through standard league based on a Impending Doom / Crit Hexblast build I saw in these forums. I didn't follow a guide, and am just trying to see how far I can get with my own devices. I'm starting to see trouble at around Tier 3-4 maps, what can I do to improve my build?

If anyone is going to be able to help then they really need to see what your setup is. I would suggest downloading Path oF Building, if you haven't already, and uploading your build into that and then sharing it here on your post.
With that, people who are crazy smart can pin point some of your weaknesses a lot easier than just guessing via the current post you've made :)

Alright so I've imported the build into POB and shared it as a link:
https://pobb.in/768rtL5ZCM6w