onigoroshi: You are even newer than the game of Go :)
Go was introduced very recently so not many players have a rating yet. Just play 25 rated games and you have a rating, but only 4 to get yourself a provisional rating.
The 3 variant (9x9, 13x13, 19x19) are considered different games, so when you have a rating in one of them you don't necessarily have a rating in the other two.