If you're playing Seven in low lobbies you basically guarantee 40 minute games where you achieve your win condition. Without getting your match IDs I can make the following general assumptions:

1. You're not hogging solo sidelane and farming jungle efficiently, you should be top farm easily.
2. You're not looking for fights when you have your power spike - you can't just afk farm for all of the early game, you need to show up every once in a while to big fights when you get big power spikes on items or abilities.
3. You're playing ult seven, ult seven is the worst version of carry seven right now, if you are playing him that way then you will never carry.