[TrainOfThought]

I agree, you don't really know a person until you spend some with them IRL.
I had known my ex for about a year before we decided to start "dating."
I put the quotation marks around "dating" since we hadn't actually met yet, but we both knew we liked eachother, and we decided to meet up asap. And so we did!
Spending time IRL is sooooo different from just talking online/on the phone, and sometimes it felt like it wasn't even the same person (not necessarily a bad thing).

On the other hand, online dating can be a good way to get to know eachother before you actually meet up. My mum did it, and got married 6 months after they met up, so the possibility for it to work out is there, but don't make any huge plans until you get to know the person IRL.
I've noticed a lot of young (13-17) people date people online without actually meeting the person they're dating, even though they live in the same city! I really don't see the point of doing that, but that's OT.

I think you should slow down and try not to get TOO attached to her, meet up ASAP and THEN decide if you still think she's someone you want to be in a relationship with.