Damn man, I don't even get 100 CS by 12 and I'm Gold 1 lol.
Your first problem is that you need to realize that you are where you deserve. Its cruel, but you are most likely in bronze because you DESERVE to be there. Once you accept this fact, you can actually work on getting out. Work on the basics. Work on last hitting and warding. Try to learn a few champions EXTREMELY well as specializing is a lot more important then having general average skill on a whole bunch of different champions. It will give you an edge over other players. One of the biggest traps for lower tier players is that they believe kills are everything. They aren't. Kills help by giving the killer gold and denying that player the ability to gain experience/gold, but unless they do something with it, the kill is just a kill. The REAL important thing is OBJECTIVES. Towers, Dragon, Baron, Inhibitors, and Nexus. These are the big ones you WANT to kill over chasing kills. Taking Dragon/Baron gives your team gold and a buff(in barons case and dragon will too in S5 I believe) and taking Towers/Inhibitors denies free vision from the enemy team and allows your team more control of the map. Obviously taking the Nexus wins you the game, so it is a no brainer.
Just practice practice practice and you will improve and rise. Try using team builder or normals to practice as they are a lot less pressure and it won't tank your MMR/rating when you're trying to improve yourself.