Around 1/2 of all patients treated with an appropriate course of Isotretinoin (the active medicine in the Accutane brand) will have complete cure. Out of the other 50% that do recur, only 10-20% will require another round of therapy. Proper dosing for most patients is to achieve at total dose of around 150mg/kg of body wt, to be given over 5-6 months. Higher total doses will increase your chance of cure, most likely, as well.
Based upon the history you gave, I think you have a very good chance of staying clear, as most men will outgrow most acne by 20-21 years old anyway (and you seem to have been improving the last year anyway), and the Isotretinoin should carry you through that. With that said, I would probably have had you on about 80mg/day through your entire course to get around 150mg/kg of body wt over 5 months. Your total dose was about 116mg/kg, a little lower than I prefer. Still, given all the above information, I would expect you to stay clear/mostly clear.
85% of people don't need more than one round of Accutane - when they take the proper dosage. The majority of time I see people who need another round, one or more of the following occurred: 1. they didn't get enough total mg dosage, 2. they were inconsistent with taking their meds, 3. they didn't take their meds with food. If you took that dosage and had mild acne, you fall into the lower realm of the suggested total mg which is between 8000-16000mg total for a course. If your acne was mild, this might have been enough. If not, and you get acne back, you can always take another course and usually the second course doesn't need as many total mg because the acne isn't as bad as the first round.
"This answer has been solicited without seeing this patient and
cannot be held as true medical advice, but only opinion. Seek in-person
treatment with a trained medical professional for appropriate care."