Severe Acne and Isotretinoin Treatments, What Other Options if it Doesn't Work?

Hello. I am a 22 years old, portuguese man. I have acne since i was 15 and i use isotretinoin (orotrex) since i was 17. The first 2 years i used it within 3 months cycles. Because acne kept returning my doctor prescribed isotretinoin for 6 months cycles after which my face is completely acne clean! The problem is that after 3 months my acne returns. I'm desperate because everyone talks about 1-2 cycles of isotret. and they are completely cured. I use oil free protectors and hydratants. Need help