Did you read my reply?
Here, I'll help you.
Ex:
You: "Let's meet up later today."
Her: "Cool, I'll let you know later today or I'll let you know in the morning"
You: "No, I'm busy during the day, I've got to *invent some excuse* at *some time*, but I can see you at *your time of choice*."
Her: "Oh I don't think I can make that time."
You: "Ok that's cool, we'll catch up another time."
End Convo.
No you shouldn't demand an answer. And frankly, if you've just met the girl and only went on one date with her, you haven't built enough connection to deserve an answer.
The problem is you expect something out of the phone call. Stop expecting, start enjoying. Take the pressure off yourself, and stop trying to hook up with the girl so hard. What you're doing (again) is being desperate for her attention, this time in the form of a date. You want to basically force her to date you. That will not go out well, and women won't take that.
In my example, if she doesn't wanna plan something right now, and refuses your offer, then you hang up the phone. That way you're NOT being desperate, nor needy, and you don't care about the outcome. That is VERY attractive for a woman, because you don't need her, and you're a busy man.
The best advice, as was already posted, is get a life outside of girls. Don't sit and wait and think about what you'll say to her: it'll only make you nervous and you'll DEFINITELY screw up. Do other things, and when you're pumped, in a confident state of mind, THEN you can call her.