Cannot see my subscription to apple tv+

You would only have a subscription if you signed up for a subscription. And then it would be listed in your subscriptions overview as an active subscription for that Apple ID account.

I suggest that you contact Apple Support for further assistance, as they can look up your account details.

Get support - Apple Support to start your support request online (chat/email/callback), or phone them.

It is possible to browse through all content available on Apple TV Plus as well as access a few episodes of most series without a subscription. If it is not showing under the account then it means there is not currently an active subscription for that service.

How to cancel a subscription from Apple - Apple Support

You can cancel subscriptions on Mac, PC, iPhone, or iPad.

You can also manage (video content) subscriptions on the Apple TV box (4th generation or later).

You can also manage (video content) subscriptions in the Apple TV app on third party devices.