I’m not sure where you got that idea. The Premium plan is an individual plan, for a single user. There is also a Free Organization, which allows 2 users to become members of the Organization, but this has nothing to do with Premium — the Free Individual Account and the Premium Individual Account both include the Free Organization feature (so you don’t need to upgrade to Premium to set up an Organization of 2 users).
If this was the reason that you upgraded to Premium, you can get a refund.
The only personal plan that includes Premium features for all members is the Families Organization plan (which includes up to 6 users with access to Premium features).
Here is a comparison of the various personal plans:
https://bitwarden.com/help/about-bitwarden-plans/#compare-personal-plans