you had 2GB worth of growth because of the growth factor of 10%, the mdf was almost 20Gb, so it grew by 2GB. When it was only 3GB it would have grown by only 0.3GB. Thats the danger of % growth factors, the amount of growth rises exponentially.

If your backup is 19GB big, thats how much data you have in the database.

did the reindex change the fill factor? Otherwise a lot of data is being added to your database.