Is my Accutane dosage accurate @ 20mg twice a day? Side effects are only excessively dry lips and noticeably thinner hair.

I'm 5ft 11, 175lbs. I'm 3 months in. I was also never asked my weight during the initial prescription so I wonder how he determined the dosage. I feel like this doc might be wasting my time. I'd rather not be on this for 8 months (if you follow the 1 mg per kg) if I can be done in 5. I'd also rather take a proper dosage and get the desired results. I've made an appointment to discuss upping my dosage, but as I've lost a little faith, I was looking for second opinions.