Relatively speaking, 5 months between DQ and interview is a long time. The majority of consulates, it's like a month or 2 max. Montreal, despite being a neighbour consulate, takes a long time. It doesn't make complete sense, but it is what it is.
I do feel really awful for all of you waiting. Like I said, we'd prepared to be in Canada for one Christmas, but ended up with a "bonus" second Christmas. The CBP and CBSA agents would just shake their heads because hubs had flown all of our Christmas tree decorations in extra baggage home after our first Christmas, anticipating we'd all be reunited at our US home, only to turn around and have to haul them back. It was disheartening, but we made the best of it. We took advantage of being able to go tubing in the Rockies (we were in AB), took a lot of photos of the beautiful snow capped peaks and the evergreen trees blanketed and tried to really soak in the White Christmas. The snowless Christmases in Texas where you can bbq in flip flops on December 25th is a bit weird when you've always had snow growing up. We tried to cherish it because it would inevitably be changing - it's easy to get hung up in the negative, but it's also important to live in the moment and find the small wins and silver linings.