Wanting Zed Advice (Any and All Possible)

Hi, first of all let me introduce myself. I am Grimspeake, a Silver V player. Its been about 50-60 games I've had in ranked over the past couple months, mostly a lot of ups and downs but never any real progress. Lately I've been trying to learn Zed and have found great success in playing him. While I find he is hard to completely carry with and basically single handily win games he is however very efficient for helping me get my team-mates out of sticky situations during laning phase. I pride myself on my laning phase and consider it to be more developed then where I am currently placed, unfortunately I cannot say the say about my late game. (mid game is just bullshit because it takes my team 15 minutes to group up after the other team already has wrecked mid, but nonetheless thats neither here nor there.) Well to keep this rather moderate in size, I am curious about how to improve my late game with Zed. How can I help my team finish the game without having to split push or backdoor a nexus and what can I do when the other team starts to build items to counter me, ex. QSS or Zonya's. Thank you for your time reading this and thank you in advance if you will give me genuine feedback! It will be much appreciated, anyways take care. I'm going to be going to bed now and will be checking up on this again on this in the morning. Hope you also have a good night. =)

P.S. I'll still take any advice anyone wants to offer me about Zed, hes quickly becoming my favorite champion. Also, one quick thought before I end this post, what do I do in the situation that I'm being focused or cc'd in team fights?