Hi millx,
If you do not have access to a trusted device and don't know the trusted phone number, there wouldn't be a way to recover the account.
We suggest asking friends and family if they still have that old phone number. Additionally, you may be able to contact the carrier you were using at the time to see if they can provide that information.
If you are able to remember or retrieve the trusted phone number, you can request account recovery using these steps: How to use account recovery when you can’t reset your Apple ID password - Apple Support
While you do not need access to the trusted phone number to start account recovery, you do have to know it in order to start the process.
We hope that helps.
Take care.