I've known people that took longer than 90 days (sometimes years) but most of the time in my experience, the situation has been that people have astral experiences, expect all of them to be RTZ OBEs and reject anything that doesn't fit in with that experience, assuming 'it wasn't real' or 'it was something else'.
Technically, you haven't failed, it's just taking you longer. I'm sure we can figure it out.