Selfish gameplay is most likely the reason you are stuck. You probably do not want to hear it, and you mite even yell at your monitor in rage, but it is true. In a game where everyone is trading and looking to win every 1v1 without a moment of hesitation, you forget about everyone else besides you. While you are hunting that Omen, pushing in hoping every single single shot is a headshot, you forget about your objective. You forget that you could easily be holding potential rotation for your sage who is doing her job. You forget about the two guys on site the Breach just ulted. When your team dies, and you finally kill that Omen, and the three enemies left are 50 - 80 hp each, you kill two of them and die.

You netted yourself three kills. No one can call your shit, you have more kills. Rinse, repeat, until your team either wins, or you lose and never think that it could have been your fault. You have more kills though, and you even clutched a couple rounds with the cleanup. You are the true carry.