I can't talk to people I don't know, especially adults, what's wrong with me?

nothing is wrong with you, it's completely normal. I'm the exact same way :)

Absolutely nothing is wrong with you. It is actually normal to be nervous when talking to new people, and especially adults. Almost everyone is. It is just some people are better at hiding it than others. Just ake a deep breath and act like it doesn't bother you. That is what got me through. I learned if you smile and fake the confidence you make friends quickly, and you won't need to fake it for long.