I second, third, and fourth the suggestion that henna is the problem. If your strands are coarse, you likely don't need that extra protein. I wouldn't say stop, but cut back.

My hair started retaining length better when I did what AmberBrown said (getting my hair wet more), and also when I started deep conditioning every 1-2 weeks. So I don't know exactly what helped. Good luck finding out moisture balance!
last relaxer 08/08/09
all natural since 7/30/10

Shrinkage happens.