FOUND...LINK IN COMMENTS

I read this story a couple years ago, and it may have been a couple years old, at the time.

Dean waa cursed and turned female. He was told the curse wouldn't be broken until he suffered great hurt or lost something he truly loved...something to that end.

Woman Dean is hunting with Sam (and evtually other stuff) for about a year, and unbeknownst to Sam, becomes pregnant. Cue great loss, and he becomes male, again. Lots of angsty hurty stuff ensues.

I seem to remember it being longer, and their were definitely a few timestamps, including one about adopting children who's parents were killed by demons, and another about getting glasses.

Help me Obi Wan!