JWM, I'm really not familiar with the intricacies of dutasteride but I would not be worried yet at the 6 month mark.
I would assume that introduction of dutasteride into your system would introduce an element of hormonal instability in the initial months. In time, your body would find a new baseline, and with that stability the med could begin to start making a consistent impact on the mechanics of your hair growth.
At that point, the "three month" timetable would begin, in which you just have to wait until the first of the dutasteride-affected hairs starts reaching your scalp line. Even then you might not notice anything, as a stray strand here or there that is fortified from the effects of dutasteride wouldn't be noticeable. You might have to wait several more months before a critical mass of fortified hairs cycles through before you could even expect to see any sort of a change.
Obviously I can't make any statements with authority about your situation in particular, but I can say that I do think six months is too soon to make judgements about dutasteride in your case. Give it time to work, and anyone here who has gone through an male pattern baldness treatment process over an extended period of time (like I have) will tell you that it takes at least a year before you can accurately make any claims.
As for your shed hair, the fact that it shed is an indication that those hairs were probably already in resting phase. It's not like the dutasteride "burned" or severed them off! What is important is what happens when those follicles sprout new hairs. Hopefully, the new sprouts will be fortified with dutasteride and be thicker. They may, on this first cycle, be similar in thickness to your former hair or perhaps even a bit more thin. It may take a cycle or two before the hair starts responding in a cosmetically acceptable way. But, one thing we do know is that, at the very least, the dutasteride should not make the new hairs any more thin than they would have been without the dutasteride.
You really have to be patient. I KNOW that there are up and down days, even weeks. But the only true way to determine if dutasteride will help is to continue the regimen in a regular and disciplined way over a long period of time, at least a year. These drugs are not like fertilizer for the lawn.
Hang in there, chin up, and all my best.