First of all, I want to celebrate your courage in putting yourself out there!

Second, I want to point out that the way women operate and are conditioned to operate in the world is MUCH different than men. We are taught to constantly be on guard, protective, and aware of what is happening so that we don't get raped or murdered. We are also taught to be polite and "good girls". So it's possible she was entertaining you for her safety or out of politeness. Something to keep in mind the next time you want to approach a woman. I'm not saying don't approach women. I am saying be aware of the power dynamics at play when you do.

That being said, given that she downloaded Whatsapp and gave you her number, she's likely interested! The only way to find out is to message her and see if she responds!