That is a lot of psychic energy over the years. Didn't is cause enough disturbance in your home for others to be affected and take note that something very strange was going on? You say at the top of your writing that she came to play with "us", so the influence was pretty overwhelmingly strong if it involved more than you. Did anyone ever suggest doing a cleansing since the haunting was so pervasive?
I would go back to the history of the home where this occurred, interview your siblings and the adults to see what they remember or how they perceived the haunting. The history of the house and the area is going to no doubt give you answers. It will take work, time and an ability to work an objective angle but you can get it done. Maybe there is a valid ghost hunters or paranormal group in your area that can offer some help.
The best to you!