Do I need to be enrolled in courses full time to remain on my F1 VISA?

Yes. Undergraduate students must be enrolled in at least 12 credit hours per semester (9 credit hours must be in person) and graduate students must be enrolled in 9 credit hours per semester (6 credit hours must be in person) to maintain full-time status.  There are exceptions for a reduced course load. See your DSO if you feel you qualify for one of these exceptions as it must be approved in advance.