If your mentality is 'i just can't win when my team feeds'
You will not climb. I've played a lot of games and what i have to say is that a lot are surprisingly winnable through sheer player skill. I just finished an 'unwinnable game'. My bot/mid had a combined score of 3/25 at 20 MINUTES. And we still won. Not because they just decided to ball up, no. I put on my bootstraps and said "this is not gonna be easy" and carried my team.
Get used to having to be 9/2/0 by 10 minutes. You want to be diamond/masters/challenger, you're gonna have to win those 'unwinnable' games.