hm let's see.
actually quite remarkable that you not #closed her but that you already slept in the same bed together.
I think the note wasn't a bad idea.
I think you should not call her. It could demonstrate that you are too needy.
You say she is quite busy with her work, so 4 days is not that much time.
Wait until she'll call you back
(you doesn't got her phonenumber so if you call her it is quite strange because she didn't gave it to you as you already said)
If she had a fun night what I expect from the story you tell she definately didn't forget you.
Maybe it's a test from her side to see how you are.
Maybe she will call you about a week (or two)
When she does. Don't refer too much about the last time. Show that she needs to be glad that you were her company that day.