Now that I think about it, maybe it did even better. It sold 7.4M in 2010 only, but it had strong initial sales when The Fame Monster was released in late 2009 and sold well in 2011, too (it topped the 3M mark in the US).
Do you have a breakdown of her bigger singles? I just have a hard time believing "Poker Face" or "Bad Romance" sold like 8 million outside of the USA, which is far and away the biggest digital market. Most countries, especially back in 2009, had/still have very weak digital single markets.
Poker Face sold 10M WW in 2008-2009 only. After that, it has sold 2M digital sales in the US (it was at 4.5M at the end of 2009 and now it is at 6.5M), so we have 12M+. Add up the rest of the world, and the total is close to that.
Bad Romance sold 9.4M WW in 2010 only, add up 2009 sales (almost 2M only in the US) and the fact it is still selling in every iTunes.
The Fame + The Fame Monster = 15M
Born this way = 5.5M
Other releases (includes remixes + DVDS) = 1.5M
Just dance = 8M
Poker Face = 12M
Lovegame = 3M
Paparazzi = 4.5M
Bad Romance = 11M
Telephone = 8M
Alejandro = 4.5M
Born this way = 6.5M
Judas = 2M
The edge of glory = 3.5M
You and I = 2M
Marry the night = 0.8M
album tracks and others = 3.5M
Total album sales = 22M
Total single sales = 69,3M
91 Million RECORDS is my personal estimations on her sales ......
She is really really far away from selling the 50M albums WW .. probably she never reach it .... most of it records sales comes from singles .... and her singles are selling less and less everyday .... from Poker Face to Marry the night