You might be overthinking things, but that's alright. You can continue talking to her or just look around and observe the world. Essentially, you just want to give off a "This is no big deal" vibe when it may or may not be a big deal to you. Doesn't matter what you feel, but she feels. If you are comfortable when she is putting her number in your phone or vice versa, then she will feel the same, usually (mirror neurons)