I am flying TATL with an onward domestic flight on 10/12. I'm booked in Y but applied a SWU. As I write this we are well within the 100-hour window at which the ug can be confirmed. I am still waitlisted for the TATL leg, although the domestic leg cleared weeks ago. Flightstats shows F:2 C:9 Y:2 so it is a pretty full flight. I am booked into seat 17G on a 777, which is a bulkhead aisle in E+. It's not the worst seat, but if they need it for a parent with infant I could get stuck in a middle seat in E-. Given there are more seats available in C than in Y at present, I expected my ug to clear by now. Does this seem weird to anyone else? Should I be concerned enough to call the 1K desk to make sure my ug was applied correctly?

Furthermore, I don't want to waste a SWU on a domestic flight. Can I cancel the SWU at the airport when I check in if it looks like the TATL portion won't clear?