It doesn’t matter if it’s your own observation, only whether there is another ID on the observation already when the subspecies is added. If you had put the subspecies as the initial ID, then it would have immediately been at subspecies.
Obligatory link to subspecies discussion: https://forum.inaturalist.org/t/leading-subspecies-ids-should-change-the-obs-taxon-like-leading-ids-of-other-ranks/139