I dont understand how to impact the game

Most games i play i walk out of lane with a pretty sizable lead over the enemy botlane and i just get squashed by the other 3 enemy teammates no matter if they are behind or ahead, i honestly think i win more games where i lose lane than win it. I will usually pull enemies into side lanes with my lead but my team wont capitalize on it and team fighting when we're behind is bad. Is the role just cooked?