Feeling lost in late Game

Hi fellow emperors, I really need some help. I played the game when i was a child and came back a few weeks ago and since then I try to improve. I watched a couple of guides and tried to get a grasp on some BOs. While I for sure have a lot of things to improve regarding my early game, I at least have an idea what those things are. On the other hand I seem to be completly lost during the later stages of the game. I lost the last 5 games in imp. Sometimes I even was ahead slightly but then completly lost it, when the big fight started and I simply don't know what I have to focus on the most. I know the concept of counters, I have kind of decent micro(played a lot of moba games) but I simply loose. Do you guys have any tipps or good resources that focus on that specific topic?