If you are always the one to initiate contact in all of your friendships, that does merit a second look, in my opinion. It could just be that you are more gregarious and form friendships with people who are a bit more withdrawn.

When I feel like my friendships are getting one sided in that way, I lay low and wait for the other person to take a turn initiating contact. Sometimes they do, sometimes they don't, but either way I have a better idea of how close our friendship really is