TIL balance is bad right now

I was playing jungle, the other team had a jungle. We had vision on his red thanks to a kind support so I knew where he started and when he would be at blue. I rushed through my jungle so I could go to counter jungle him and fight him near his blue. "Kog jungle!? I bet his early game will be awful, what a good chance for me to snowball!" I thought to myself. When I got there he had just hit level 3, and I was also level 3. I had blue buff and red, while he only had red. We were both full health with the exact same items...

I saw him and jumped on him, landing every ability with the added damage from isolation. "This is perfect!" I thought, as there could not be a more optimal situation, a lone weak early game ADC vs the terrifying bug! Except, it wasn't, he proceeded to not kite, or flash or anything, just stand there and burst me before I could burst him. I was playing an ad ASSASSIN, who ran into maybe the "weakest" early game ad carry by himself in the jungle and I could not burst him down after landing every ability and auto...