Retaking courses/low points

Hi. I’m a second year at a CC in California(IE area). I’m planning to apply for the nursing program at the end of the year. So far I got a B in anatomy 1 and C in anatomy 2. I’m gonna take microbio in fall 2021.  I wanted to retake anatomy 2 for a higher grade, but my school makes us request to retake a class where you didn’t fail. But on the paper it says that I’m not allowed to retake the class cause I got a passing grade and I don’t have any extreme reason for retaking the class (for example death in family, illness, etc). Has anyone had this problem. My current GPA in general is 3.0 and with my current prerequisite grades I don’t have high points so I feel like I won’t get into the program even if I do well on the TEAS. I see everybody has their points in the 70s but mine would maybe be in the 60s. Any advice??