If you think you did well on the other 2 interviews, I think you should just call them and make it post dec, I delayed one of my interviews a few weeks ago and saved over $300 in flights!!! just because it was on short notice.
I would go. I'v had interviews where I felt like I was a shoe in but apparently that was not the case for some schools. My stats were not stellar either. So if you know you are very competitive then it might be worth a shot to wait.
I actually postponed mine post-Dec and I have lower stats with only two interviews so far. I would go to either of the schools I got interviewed at over Western (despite the lack of a visit). However, if I don't get into one of those, I may be kicking myself in the arse for not going.