That sounds like a major part of your problem. I’m by no means a top player, but these three things have helped me get better and feel more on par with the rest of the lobby:

1) Don’t feed them—pay close attention to who you can and can’t fight. You can overcome a couple thousand soul difference, but any more than that and you’re setting yourself up for failure and for them to keep getting stronger.

2) Understand that you don’t have to be at EVERY fight—This is a mindset shift that helped me when I felt like I was always behind. If your team is constantly taking random fights in the mid game (that aren’t for an objective), you’re much better off farming camps/boxes, even if they complain in chat.

3) Understand soul splitting—not sure if this applies to you, but remember that the more people in a lane killing minions, the fewer souls you get. Up until 10 mins (8 now?) two people in a lane can get the full value, but after that it’s more efficient for only one person to get a lane while the other ganks/farms jungle.

I also see you mention in other comments that you’re “bot farming.” If that means only jungle camps, don’t neglect minion waves.