Microsoft 365 features that help users manage their subscriptions, account settings, and billing information.
If you did not cancel the Personal subscription first, on the link below they provide the details of what happens when you upgrade to a version of Microsoft 365 that has more features like going from the Personal version to the Family version, you are charged for the new subscription, then the remaining days on your previous subscription should be converted to the new subscription on a pro-rata percentage basis.
Log into your Microsoft account on this link, check the expiry date on the new subscription, is it now indicated as more than the 1 year subscription?