Hi letsgo
It sounds like you have some great experience already! I'm not sure what your other stats are regarding GPA and such, but I definitely think that doing a mission trip would be a good idea, for a variety of reasons. I was accepted to UofT this year and I have some international experience at a high school in Tanzania so maybe that helped? I may also suggest that you gain some experience working with a population other than children this year, perhaps in a geriatric setting? I think this would make your application very well rounded and it would show a lot of diversity in your experience. This is something that was suggested to me by the faculty members at the info session last year.
Hope this helps and best of luck!