Time skips back and forth so randomly that I can't keep up with it man maybe I'm just dumb...

Not dumb, the story does alot of jumping from past to present and at times, it's very jarring.

The story is like that so we could understand what happened in the past- Just the past wei ying is long haired- while the future got pony tail^^ Lan Wangji is also taller lol and they got juniors- there u wont be confused.