If anything I would have thought the biggest age jump would have been between 10 and 11 since it seemed like 10 spent a lot of time roaming around the galaxy and time and generally going on his own merry way sans companions or at least companions we were told about. I mean hell he married 'Good Queen Bess' so... I mean let's face it, he could have lived with her for even the average life span of like 60-70 years - but its sorta quasi accepted that it was only a few years he spent traveling around
The Doctor gives his age in Voyage of the Damned as 903 and in The End of Time he says he's 906, so clearly between those two episodes there's only three years. After RTD established the Ninth Doctor was 900 years old, he consistently added one year to that age as each season when by, which Moffat continued until seasons 6 and 7 where the Doctor starts aging a couple hundred years.