Two other things you could try, regular protein (as much as ur hair can handle) and sealing your ends.
I have noticed that once my hair passes shoulder/armpit length I have to do more to keep my ends in check.. Being gentle is a given, but thats not the only culprit.. now I have to go in and do extra to my ends (last 3 inches or so) because my regular routine will have majority of my hair feeling great and my ends lackluster.
So basically, if you feel your regimen is solid.. pay extra attention to the ends. Whatever you do to your hair do more to them, if you dont seal your length seal the ends, if you seal with oil seal the ends with butter etc etc. Makes a major difference for me esp since my hair is fine & tends to be more fragile even at its healthiest.
& know a lot of people cowash solely, but generally its done more often. I think adthomas was trying to precaution you that going 2 weeks in a protective style then only cowashing might not be enough to rid your scalp of the buildup. Cowashing is good for moisture, buuuut buildup can stunt growth and cause breakage.
& if you need a trim, do that first! Maintenance from that fresh start is easier than nursing dead ends.