Even if you use both scrolls and add it to con she will most likely just keep giving to int and wis and occasionally agi.
If you haven't done all the quests that give scrolls I would stop leveling her right now and get those scrolls and keep adding all the points to con. If you can't obtain anymore scrolls then the only thing I can suggest is to make sure that a lot of the stats she gets after you rb her go to con.

Good luck ^.^