*takes the hand of a period drama writer gently* A queen consort is not a queen regnant. A dowager queen is not a queen regnant either.
There is very little intrinsic institutional power in queenship. The power a consort, dowager, or queen mother has depends mostly on how much the reigning sovereign (usually a man) is willing to grant her. Needing a queen to serve as regent is exceptionally rare, and the regent is more often a male relative.
I know this is a bit of a bummer. I'm sorry.
For clarity:
Queen regnant: woman who rules in her own right, not on behalf of someone else.
Regent: Someone who temporarily assumes the powers of the monarch on account of the monarch being too young or too incapacitated to govern.
Queen consort: Woman who is married to the monarch.
Dowager queen: Woman who was married to the monarch. The monarch is dead, and she is owed support as his widow.
Queen mother: Woman who is the mother of the monarch. Usually the dowager queen, though there are exceptions if there isn't a straight line of succession.
