More Useful Stuff
Saying something out loud makes it seem more real and she might be assessing your long-term boyfriend potential before announcing your status to the world prematurely (like your friend on Facebook who has more relationship updates on his wall than friends). Calm down, this doesn’t mean she’s not really into you. Wait it out and don’t worry.
Now’s not the time to act insecurely, but you are entitled to clarify if you feel you’ve misread her signals. Reassure her of your commitment by subtly introducing her as your girlfriend when the opportunity arises and, if it’s still an issue, bring it up casually like, “Hey, do they know we’re dating?”.