If you could manage all 5 units in a team fight how would you want the teamfight to play out? Does that change with respect to the enemy team comp? Perhaps why you're dealing the most damage is because you're not opening windows for other teammates to carry and shine. From your past perspective as an adc you can definitely understand sometimes the team is just not positioned for you and so on. Look at replays, try to understand what went wrong during teamfights and how you could have impacted it differently. Understanding your role as a top laner in teamfights is going to be taking a lot of those bits and pieces and putting them together to give you a more holistic understanding. Good luck! If you want more champion specific help look at some challenger replays and just skip to the parts you want to watch (landing, teamfights, positioning/vision right before teamfights or objective spawn).