Using Outlook for Android for personal email and calendar management
@Samantha Hemphill If you are using a Microsoft email (outlook.com, hotmail.com, etc.), have you tried logging into that account via Outlook on the web? Your message should have synced to the email server and would be in the draft folder of the web version of Outlook. This is the link to Outlook online: https://outlook.live.com/
Check the other inbox folders too in case the message was somehow moved after you last accessed it. Mobile phone screens can be challenging especially when you are focused on a certain task.
And if you haven't already, restart the Outlook app on your phone to ensure a good sync with Outlook servers.
FYI, if you are using a non-Microsoft email, then your recovery options are limited. I hope you find it.