You made plans by email. It seems completely reasonable and expected, that she keep contacting you by email. People usually contact in their preferred method first. I always take the lead and contact back, in whatever way someone contacts me first. Most people I know personally, do the same. She didn't call, because you didn't call. You suggested another day, so she was probably going to email you back, to plan for another day. I
suggest calling or texting first next time, so maybe she will respond in that manner.
I've known a lot of flaky people in my life. The wishy-washy flakes never contact several times in ANY way, to find time to hang out.Maybe, they will contact back once or show up late, or whatever. They don't act like your friend, who genuinely seems to have had difficulty getting things together.