it is quite natural to drop early on a first preg. or if you haven't had a birth in quite a while. On proceeding pregs., it is not unusual to not drop until right before labor.
You are fine. My first preg. baby was extremetly low and head down the ENTIRE preg. (so low that they couldn't get her head on sonos often due to my pubic bone) and she was always ontop of my bladder. My dr. was never worried about this and she was born a week before my due date, not considered early by any OB (anything 38 weeks or over is full term).
Best of luck!
T.