This is one of my favorite ways to stay busy too!
Here are a few D names I like for you. I starred a few that I really love. Also, a few of the boy names could probably be used for a girl too, since you've already done a bit of gender-bending with Dawsyn. I could see Devin and Dylan in either category for you.
Boys:Dalton*DamianDamonDashiell* (Love this but nn Dash is probably too confusing with Dax)DavisDeckerDeaconDeclanDevinDylan/Dillon*DominicDuncan
I also really love the idea of choosing another non-D name with a D nickname, in order to even it out a little since Drew is the only one without a true "D" name. It's a lot harder for me to think of D nicknames that don't have a D full name though.
Alexandra nn Drea -- Love this!Addicyn nn Dicey -- I'm not wild about Addicyn, I'm tired of the name in general and that spelling is really confusing/unattractive to me. (Sorry) Adelle/Adeline/Adelaide/Madeline nn Delle or Della or DaleyAdair nn Dara (love this!)
The only names I could think of were not a great match to your style. (ie Eudora/Theadora nn Dori). I'll keep thinking though!