I finally received a response on my ticket:
the estimate is ONLY AN ESTIMATE. Until the game goes Free to play, this amount is IMPERMANENT, and only a GUESS as to how many you will end up with. Until the game goes free to play, it's a general idea, not a true value.
When it goes f2p, there will be an "accurate" accounting, and values will be credited, and THEN, if the value seems off, let them know, and they will adjust. Right now, we don't even HAVE coins, we only see an estimate, none have been credited to us.
That would explain why any free months were not accounted for.