I'm with momofdd on the interview. My S, who will be attending Colby in the fall, was not able to schedule an interview (no availability for the day we visited) but we went ahead and he wrote about his visit, mentioned the name of the guide, etc. on his "Why Colby?" essay. He also mentioned he wanted to have an interview, but could not get a slot.
Here's a link to what Dory Streett, a Colby admissions officer suggested in her blog on what Colby is looking for. This is worth reading; my son followed her advice and got in regular decision. His stats are similar to yours, no sports activities, very focused ECs and he has national and state writing awards. I think you have a very good shot, and ED will help.
Colby College | News & Events | Read Blog Post
Best of luck.