Post-adolescent acne is actually quite common. I don't know why in women this tends to affect the chin and jaw in particular, but it seems to. In any case, the treatments you've tried are appropriate,m but if they've been used long enough to convince your dermatologist that they have failed, then Accutane would indeed be a reasonable option, and quite likely to help a great deal, or perhaps even end your problem altogether. Accutane needs to be used with care (avoiding pregnancy for 6 months, checking lipid levels), but most patients tolerate the 20-week course with ease, and are very happy with results. Accutane has a track record extending back 25 years. I think you should explore this with your skin doctor.
Best.
Dr. Rockoff