It does sound like you have tried almost everything for acne treatment, and I am sorry to hear that you have not had much success with any of the treatments you have tried so far. Most of the things that you mention having tried are the typical things that I recommend, so I do not have much to add
other than to say that you definitely need to get back to see your dermatologist
It is possible that a sustained regimen of retinoids and antibiotics could work for you. I know you have tried this, but I only raise it again because I do not know how long you tried these treatments for and if you tried them at the same time. Severe acne usually requires multiple medications at the same time for long periods of time.
If you have in fact done this, then you are right that the only real treatment left is Accutane. Accutane is an excellent medicine that works really well to control acne. The major side effect is that it causes birth defects if you were to become pregnant. Therefore, in order to obtain Accutane, you would need to be on birth control
and sign a contract agreeing to stay on it as long as you were taking the Accutane.