She looks to me like she's in the developing/building phase. I like to get one good lock per month during that phase until I see a nice, big ovulation from my girls. Ovys are quite obvious, looking very much so like they swallowed a football. She's not quite there yet, but could certainly be getting close.
Along those lines, have you see Mark Mandic's Breeding Pictorial? It's a very useful guide when it comes to knowing what physical signs to look for along the way: http://ballpython.ca/breeding/.