So, it sounds like I'm doing all right. I mean, I feel I'm making myself as safe as I can without holding up traffic. I do use a mirror, and I'm getting better at being proactive in places that can be difficult for me to get to the lane I want to be in. After reading comments in other forums and threads, I thought maybe I was doing something wrong. I rarely see other bike commuters, so it's not like I can watch and see what they do.