I don't know what to do with a lead mid-late game.

I usually can get ahead in lane, but I don't know what to do afterwards... It's either I cannot impact the rest of the map enough, or I concede lane pressure by roaming to mid, top, or bot. Doesn't matter whether I have ignite or TP (in either top or mid). If you look at my OP.GG, the 14/6 game is a prime example. Their corki got pretty fed and was able to do more then me. What are some things I can do to use my lead elsewhere on the map? Do I just say screw it and lose the lane pressure? Do i continue to force my lead top? I don't know... It just seems like I do really well, but cannot close it out with my lead... Any advice is appreciated, I'm tired of being a low diamond/high plat player... I struggle at this tier every time on any smurf account because I cannot just roll over people like I can in Plat 5 and below, these players just make less mistakes and don't give me as many opportunities to do what I want to do. Roaming seems to be a weakness I have, but I either over-roam and fall really behind on CS and XP, or don't roam at all. I play Yasuo, so he isn't the best roaming champion; but hes my strongest champion in terms of skill. I'm at a cross-roads, what do higher elo players do here that I do not? I can hit mid-high platinum with 70%+ winrates, but I tank hard past that; why is that? What can I do to improve at roaming and impacting the map? This cycle of doing well and losing is becoming extremely frustrating and very tilting...

OP.GG: https://na.op.gg/summoner/userName=Deftssuo