I am the same way. I find that this is a poorly understood phenomena - there are many well-intentioned people who have a difficult time comprehending that it's even possible for someone genuinely ENJOY a passive role in conversation, as opposed to the typical view that they're just bad at getting their voice in.Being an introvert, I really do prefer to just listen instead of being part of the conversation. It's who I am. I love being who I am.
There are many occasions in which I enjoy having a blabbermouth around just going yap yap yap at for much of the conversation; it's less work on my part and probably pleases the other person's desire to be listened to.