I sometimes have similar questions to you. I think that people are just different, and some types of people don't feel like they need to share the ups and downs of their feelings as much as others. Quite often these people really enjoy a friend who is very excited, who can engage them with an interesting story, or excite their emotions. I had a very close boyfriend who was much less talkative than me, and as we grew closer I would often share the type of worries you express. He would just affirm that he liked things that way. I guess the main thing is to find a way to be secure that your friend enjoys your talking. Remember, he/she wouldn't be there with you if they didn't want to. Maybe ask other people in their life if they notice a similar style of communication. It sounds like you have already asked your friend directly, so this base is covered!

Good luck! I'm sure you're a very interesting person with lots to share. That's a great thing.