Sahara, welcome to PsychCentral (PC). I think you have normal teen/growing up difficulties; getting to know more people than you're accustomed to in situations that are more in your control and less structured.

When you first meet a person, one doesn't know the other person well enough (or they, you) to have a whole lot to say at first! It's easy to be part of a group conversing, just adding in on what other people think to start but not so easy to start! Watch next time you're in a conversation with a group of your friends; some people only "comment" they don't start subjects or conversations with others.

There's no "rule" or good/bad about starting conversations/friendships with new people; some people are naturally better at it or have had more practice. If you want to be someone who starts conversations, then think of 3-4 opening questions to ask someone and when everyone else is gone and it's just you two, ask one or two of those and see if you can get something interesting going.

It sounds like you have a warm and friendly personality; I wouldn't worry about anything being wrong unless you can't learn ways to practice being a conversationalist (if that's what you want). It takes a lot of practice for some people to get so their mind doesn't "go blank". But if you think of the 3-4 things that you enjoy and "wonder" if the other person does (as opposed to the "weather" :-) I'm sure you'll get more comfortable and think of even more things to talk about with new friends.