Just for reference, have we ever had a canon Jedi who had to leave the Order because of a relationship?
Personally, I don't see any reason to believe Bastila ever got pregnant at all. It seems obvious to me that she had a sister that Revan screwed and knocked up in a completely unrelated set of circumstances.
It also definitely took place before the amnesiac Revan was re-trained during the events of KotOR, but after he lost his memories.
"Grant Allen [...] had written a book about the Evolution of the Idea of God. [...] it would be much more interesting if God wrote a book about the evolution of the idea of Grant Allen." ~ G. K. Chesterton, The Everlasting Man