I'd try a protein treatment like keratin. I use the Organix 30-day straight treatment, and it doesn't fry/dry your hair and doesn't have any weird chemicals like formaldehyde or any other harsh products. It loosened my curl patter significantly which is what I wanted, but most of all, it restored my hair's proteins. I was having the same problem you are, lots of knots and breakage from not taking care of my hair (chemicals, using a brush and ripping through it, etc). It has done wonders for my hair. Also, you might want to start using an anti-breakage serum each time you wash. The Organix company makes one also.
Do you wear your hair down a lot? That could be one cause of all the knots. Keeping your hair bunned most of the time if feasible is your best bet until you get your hair back under control.
What kind of conditioner are you using to detangle when you wash?
Washing as often as you are may also be causing the knots/breakage. Is there any way you could try stretching washes out a few more days instead of every other day?
25", hennahead, CO, goal: hip