The exchange for both of our items is supposed to happen at the same time.
Exchange is the key word. It is your leverage to get your things back. If you comply and she doesn't then your leverage is gifted away. If she doesn't facilitate an exchange at a reasonable time then your attempts to arrange the exchange is your proof you tried to comply with the agreement. Of course, I'm not a lawyer so while this is common sense you need to follow local legal instructions.
Many here have faced the silence, obfuscations and delays. Negative engagement is still engagement of sorts.