A while back, me and a girl started getting close. We haven't met before, but it was a friend of mine that got her to start talking to me maybe around last year. We used to have really short conversations, neither of us really sure what to talk about. After a while, we drifted apart and never spoke again.

But the other day, she randomly popped up out of the blue, saying I was adorable, handsome, and just complimenting me in general (I'm 16). I wasn't sure if it was her or not, so I just went along with it, saying thank you etc.
I found out she wasn't, and for the past few days after I've got home from work/college, we've sat on Skype/FaceTime talking literally all might. From literally 5-12. On the first night, we really opened up, which is something I never do because I'm a really closed/sensitive/emotional person. But for once, I felt really comfortable around a girl talking about personal things, I felt confident because she kept complimenting me, and we just clicked. There wasn't a long silence, and even if there was a short one, it wasn't awkward or anything. She says it was a "comfortable silence".

It probably sounds weird to some, but I find it cute. But when we're on Skype/FaceTime, she always takes a screenshot thing with her iPhone of me on, and then puts it on instagram with a really cute caption.
A couple of times she's been with her friend when she's been on, and her friend refers to me as her "boyfriend". Any ideas as to why?

Now I've always been attracted to this girl, but I'm just not sure what to do. I've had relationships in the past, but with this girl it seems different because we can relate to each other so much and talk about anything.
I don't exactly want to rush into things because I don't want to ruin it, but any advice would be helpful.