The phrase "actually doubted" is correct and usable in written English.
It can be used when expressing a realization or acknowledgment of skepticism regarding a statement or belief.
Example: "Despite her confident demeanor, I actually doubted her ability to complete the project on time."
Alternatives: "truly questioned" or "genuinely doubted".
But, when I saw the video, I actually doubted a little bit.
Mr. Fujiwara said he had never seen a wildcat in his 68 years here and actually doubted its existence.
Silly old social-engineering-type liberal that I am, I had actually doubted that marriage education might be helpful to couples doomed to spend their married lives on separate cots in the shelter.
Yet, empirical inquiries also require a starting place if not a necessarily true one, at least an indubitable one, that is, one that is not actually doubted.
"Until recently people actually doubted that it existed". She said selling Star Wars merchandise was relatively new for the firm, which specialises in toys.
During my MBA journey, I would actually doubt myself, my goals, and even sometimes be questioned by other people.
No one actually doubts that, even if Holloway has become convinced of the need to change his image.
I actually doubt that a single P.B.R. drinker who hears the history of Pabst Brewing will give up the beer as a result.
Division along cultural and political lines has sharpened, to the point at which many actually doubt the sincerity and basic humanity of their political opponents.
I actually doubt that it is possible to see it using the refracting telescope on the Cornell campus even on a clear night because of the light pollution from north campus.
EVERY organisation does it," he shot at Della Penna, before pausing to reload and take aim at Williamson: "MW on your resume … I actually doubt that you worked for Barclays after HS there is no record of it.
