can i do part time college?

trying to join afrotc at my school, im a sophomore but i have three years left due to engineering lol. The issue is i will be forced with my small engineering college and inability to sign up for certain classes to continue these next three years with random semesters, some part time , some full time. Are there exceptions to the full time requirement? my schools full time is 12 credit hrs which i will not always meet.