Extremely worried- Last month on Accutane, still a small pimple a week.

I have been on roaccutane for nearly 6 months (20,40,40,40,40,40mg) I weigh 45kg, My acne has improved, I had moderate papular pustular acne, with became severe at the strt of the course, and then very very slowly improved little by little. I have one week left of treatment and I am still getting a small pimple once a week, It usually goes away in 3 days, but i thought by the last month I shouldn't be gettinf any pimples at all. Could my course be extendes a month or will i get a 2nd course?