Re: Should I cancel on her before she cancels on me?
The issue might lie somewhere else. Did you ever consider giving up the date talk and re-evaluate your interaction with this girl?
She's probably gonna flake again even if you reschedule, because your relationship lacks some aspects, like comfort or attraction or maybe (I hope not) both.
I'd suggest pulling back and concentrating on your conversations rather than on the date.
It's not about who I was or who I'm going to become.
It's about who I am. Do it right here, right now.