My head is a mess
Im just a bit behind you Im at like 7 weeks and like you I have super fine hair and its very straight as well but mine doesn't knot very easily. I started with short hair like 4 inches and same thing happened with me, first month stayed in sections, had a few dreads starting then at around 6 weeksI started getting more formingand also a bunch of 3 that keep joining at the roots its hard to separate them sometimes but not as much trouble as it sounds like you're having. My hair isn't looking too messy yet either apart from the oldest dreads that are sticking out and stuff.
Anyway Id just suggest to just continue separating as you are and relax a bit about the sections coming out and redoing themselves and stuff I have that a lot but in the end it'll all dread up and look awesome =]
God luck on your journey =]