My gal used to be like that too.
What we did then was we brought her out more often and if strangers want to carry her, we let them carry even if she screams her had off. Usually those strangers will pass her back to us very fast. Haha! I also brought her out with my friends kids and let them interact so she get used to having uncommon faces around. After a few months, she was ok already.
I think its just a phase they go through cos now that my gal is 2 yrs old, she will talk to strangers and say 'bye' even when they are not looking at her. lol!
so dont't worry, just try to expose her to more people and she'll be fine nce she is used to it.