Give her some space. You are being very eager, Let her miss you, don't be that guy that does this:
you - are you free Mon?
her - no
you - are you free Tue?
her - no
you - are you free Wed?
her - no
you - are you free Thu?
her - no
you - are you free Fri?
her - no
(This is chodey, an interested girl will make an alternative solution)
Next time, ask her in a way that puts
pressure on her to make plans, for example:
you- So what day of next week will you be free for that drink?
This puts pressure on
her to answer. If she says
'i'm not sure, i will let you know' and then she doesn't let you know then you know you are dealing with a flake.
if she does get back to you with a day, then happy days.
Recently, i have had a few dates where it almost went too well and surprisingly flaked. I think sometimes they think too much into and sabotage the whole thing. But i guess we are powerless to really know the real reason. If you ask her she will say the usual 'it's not you, it's me' which means it is in fact you.