Just as a heads up, the Mastery Points for Personal Story are awarded on a per-chapter basis. So once you complete Chapter 1 and earn the Achievement for it, you’ve earned the Mastery Point for Chapter 1. This includes each different starting storyline: I believe the right names are: Graduation Day, For The Legion!, Crime and Punishment, Rising to the Challenge, and Waking from the Nightmare. Similarly, whichever Order you join, there’s just one Mastery Point there.
Hopefully this helps clarify the total number of Mastery Points you should be expecting from your previous accomplishments in Tyria. That said, the different stories really are fantastic, and should definitely be experienced, but for your own pleasure, and not for Mastery Points.
If any of you still think you are missing MPs from Achievements you’ve completed, let us know via the in-game Bug Report tool and we’ll try to identify if there’s a bigger issue happening.