There are so many variables here that someone else's experience really is not helpful.
I am really glad that you are seeing a dermatologist, they really know how deal with acne given all the variables involved with that condition. A repeat course of therapy is not uncommon for many conditions. Medicine is an art not a science. We all respond differently and we just have to keep trying different things until the condition clears up, if it ever does.
I am a retired Pharmacist and I have seen several people over the years who needed more than one course of Accutane. For a many people, as they get older, their natural Testosterone levels go down and their skin does clear up to the point where normal daily skin care keeps their face acne free.