shes not a flake, shes flighty. theyre different.
she sounds needy as hell. chances are she was over for a quick validation fix and thats that.
if you follow calveless wonders advice and snap her into place at this point, youre going to lose her. how much has she invested in you in terms of time/emotion? enough that shes going to alter her behaviour for you? no way. put the hard word on her and shes going to think youre needy, the fun will flow out of your interactions, positive emotional connections will not be made and youre going to blow out.
now, it sounds like the girl is attracted to you, or at least, interested enough that shes going to keep interviewing you, which means she will probably respond to you inviting her places/engineering meetups.
so what you need to do is keep doing what you were doing before. youre busy. youre popular. you have so much shit happening in your life you couldnt really care that the girl next door is a 9, you have another 10 9s waiting for you elsewhere that you need to try see tonight. keep busting on her in a fun way. keep her having fun with you. - but at the same time, you need to get an excuse to get her over again to spend time with you, so that she can start investing emotionally and you can actually game her properly.
let her see that youre the best option available, let her decide taht she likes you/being around you, and then as soon as you know shes decided that youre sexually attractive and she wants you, TAKE CONTROL (because hot girls generally wait for a man to take the lead and seldom do so themselves) and throw her into bed with teh quickness