There is something called an ambivert, and I identify with that. It is someone who is extroverted in certain situations, and introverted in others. I was very nervous about going to graduate school because I felt I would do poorly in groups, and making presentations. I found that in the classroom where there was focus on one subject I could and did speak freely to the group. However, at parties I tend to be quiet and move to the fringe of the party. If I am comfortable one-on-one with a person I can be quite talkative and outgoing. So now I identify more with being an ambivert, but I think I put myself in situations where I became more extroverted. I think one might not need to let themselves be too defined by labels. There is always room to grow and change.