So first let me say if you want someone to duo w/ and make the games a little more tolerable I'm down to help you climb to silver if you want to duo. (As long as you don't say anything negative to teammates before a game ends at least since I don't want to carry the weight of a team that plays worse bc someone insults them)
Second, let me add, that mathematically it is up for debate as to whether or not you are feeding. Saw an interesting thread today running the numbers on someone who goes 10-10-10 (or in your case 18-8-?) vs someone who goes 0-10-30 or something like that. Long post short, if you run the numbers (bc of decreased gold on death spree) the person going 0-10-30 fed WAY less gold to the enemy than the person going 10-10 or 18-8. (You're probably giving over killing spree gold frequently so that's even more) If you go 10-1 or 10-2 you had a way better game than going 18-8 in terms of how much you fed the enemy. If you die less then the enemy has less gold and you don't have to carry as hard bc the enemy doesn't crush your team so hard. (Remember, that feeding teammate who never gets a kill is feeding less than you are currently, and so if you cut down your deaths, the enemy can't kill your noob teammates as fast and you win more team fights mid/late game and then win more games)
Anyway just food for though on an easy way to work on improving your game w/out being able to observe any game play and give better advice. Let me know if you want to duo.