Unsubscribed app is still active!
According to Apple:

Tap Cancel Subscription. If you don’t see Cancel Subscription, the subscription is already canceled and won't renew.

You stated you don't see the Cancel Subscription button so that means it's already canceled. Cancelling means that it won’t renew now at the next interval. If you want to be very safe to double check, you could reinstall the app and delete it when connected to the internet. Apple will ask if you want to cancel the subscription when you delete an app with an active subscription.

https://support.apple.com/en-us/HT202039