Hi Lukemac...
Our experience for our DD10 that we applied for the first time without portfolio and they came back and asked for more info or work samples since I didn't have collection of work samples at that time..I waited about 6 months and re-apply with work samples and accepted.
I feel the same way too, I feel that my DD is PG, but I think I didn't do a good job on how I described DD in very detail in 1st time application.

Good luck to you....