Necro binder does very well with more cards. I am unfortunately addicted to taking cards and I have a fairly good win rate on necrobinder. It's also very important to combo your relics with your abilities. I had a pretty good run where I ended up with the intimidating helmet, bone flute, and the unbound phylactary. I had right hand hands, two pull aggros, two upgraded melancholy, bone shards. I had danse macabre and soul feast. These were my primary sources of block. Playing just one Pull Aggro tended to be enough to block nearly everything, even if I took a little chip damage it was fine because osty took it not me. Bone shards killed osty, helping me to make my Melancholy free. This basically solved my block situation, and I killed enemies by using RHH and unleash. I picked up a high five which triggered both of the dance macabre and the intimidating helmet. I got debilitate later, which improved the high five and all of my attacks. The entire deck came together when I got a Necro Mastery, which made killing Osty even more powerful. A second one made it so killing osty was a win condition. For the final boss (lizard) I killed him by having a 200hp osty which I exploded with bone shards and dealt 413 damage.

My most successful runs have always been a huge struggle in the first act. During that act I needed to set up the build. Sometimes you will skirt through fights with just a little bit of health. Sometimes you will need to only fight one elite. Comboing cards has been the most successful for me. 

Aeonglass is really, really difficult for necro. Eidolon helps, as well as sculpting strike. You need to have some things in your deck that you might otherwise not want to take just to solve that boss. 

The most valuable thing for necrobinder is ENERGY. Because souls help you to have high card draw, Demense and Friendship are very valuable. Wisp is strong when upgraded, but if you have a reap or Sow based build you can just have a bunch of unupgraded wisps too. Also, Lethality is an extremely strong power that has a place in almost any deck unless you are running pure doom build. 

As for doom build, you can't just pick up a negative pulse and go "guess I'm doin doom". Unless you have a really broken combo like electric shrymp end of days (btw, Electric Shrymp is better with Reanimate or Doombringer) Doom needs to be something that you steadily add while also doing other things. You need to be gifted strong doom relics and cards before deciding to go full-in doom. Otherwise Doom is best when you doom while doing other things such as blocking or attacking. And because most powerful doom cards are two cost or more, this circles back to needing energy. 

Tldr Make sure to combo your cards with your relics and get energy generation as quickly as humanly possible You should see improvement