when you say you took "some maths" while you were a BBA, what kind of math did you take?
in regards to first-tier canadian MA programs, the first two are quite* competitive to get into unless you have sufficient math courses (i know some folks with very high GPA but not much math didn't get into either one of them), and as for Queen's, i get the feeling they are more inclined to accept canadians over internationals, and slightly less importance in math than the first two. many people from my school got into queen's last year. there were people on this board with better profiles who didn't get into queen's (internationals). since you are at carleton this year, i don't think being an international would make things disadvantageous for you..
i think it really depends on your fall term grades, and whatever econ/math courses you took as a BBA. i hope you have at least calc 1 & 2, which is absolute min., but you really should have calc 3 to have good chances in these programs. i hope you also have linear algebra, some kind of stats course which you say you have, and good grades in all those, plus good grades in upper div. econ courses. most canadian undergrads i don't think have analysis or anything like that, so if you don't have it, i don't think you'll be at a disadvantage, just that it won't give you an "edge".
good luck. i am applying to exact same canadian universities as you, in that order. i would say, excellent choice!

i know nothing of US programs.