become more outgoing, less shy

I remember when I was in elementary and middle school, I would hardly talk to anyone. I even had kids come up to me and ask me why I never talked to anyone! However, I guess somewhere between then and growing up, I started to come out of my shell. I’m not afraid of stating my opinion for the most part and I don’t find it extremely difficult to strike up conversations. However, I do sometimes get quite nervous in uncomfortable situations and I even have a stuttering problem sometimes (which is quite embarrassing :() I don’t know if other people have this problem, but when I am among others who know each other and they are all talking, I find it incredibly hard to enter their conversation, because I don’t know what to talk about! I don’t know if my problem has more to do with being too shy or just not having anything to say, but sometimes it is a bit hard to interact with people and I need to put a stop to that and get out of my little shell.