I've served IPAs at 35* and not lost flavor. Add to that the bottles of commercial IPAs in my fridge that do just fine at 33-34*.
Yes, on the bittering addition: one 10 ml hopshot at 60 minutes.
The hydrometer sample that I collected at kegging smelled wonderful, and tasted quite good even prior to any carbonation. I did forget to dump the yeast prior to dry-hopping this time, so that could contribute, but I didn't have any issues when I was fermenting and dry-hopping in a carboy.
I do think the carbonation is the best bet at this point, but I'm regularly amazed at the stark difference a day can make. I don't know if it is my tastebuds being ruined by something I ate, or my body's chemistry is different, minor allergies, or what, but one day a beer will be marvelous and the next boring - so that may be it too.