If you can do a basic listing with your phone, purely to upload the photos, you might be able to then revise them on your computer to do what you need to do. Can you schedule listings to start later on your phone? I've never used to app to create listings so am not sure of its limitations. It might at least get you to a point where you can have them on your selling page and revise them before they go live.

Good luck, I'm sure this is really doing your head in!