I can't carry as top lane. Please help

So I'm plat 5 right now and I was plat 4 about a week ago (week ago). And I just can't carry as top lane even though I win my lane most of the time. For example: last game I was playing akali vs rumble top lane and I got 2 kills in my lane roamed bot and got 2 assists by helping my team kill rengar and corki but the score was already something like 5-12 in their favor and in the end we lost with me going 8/7/4 with a 2k gold lead over the rumble and most gold on my team. Maybe I'm just losing because I'm not warding enough, maybe I need to pick better champs for top lane, or maybe I just need to roam more (I think I might stay in my lane too long because I like getting big cs scores and denying the enemy laner from their cs).