Cursed?

For some reason, I've been getting bad teams lately, and I know how you're supposed to "carry" them and "encourage them", But how can you carry 2 Lanes at once and a feeding jg without letting the enemy laner take your tower? I've won 5/20 of the past 20 games as in match history, I'll admit i've had some bad games. but most of my losses are because of my feeding team that has no idea what they're doing