hi... see acne is a harmonal concern and always happens because of that...its not because of pollution...its a phase of life...acne usually starts at the age of 13 to 14 and may contyinue till the age of 25 to 26...according to your age you should not be having a single pimple on your face but still you are getting few pimples monthly that means there might be something wrong with your harmones..acne being a harmoonal concern itmay recur as well but still we need to treat acne because we need to prevent complications of acne...is your mc regular,,, you can continue your isotretinoin medicine but i feel you require a proper harmonal work up...you can also try oral contraceptive pills...dont do dermroller and isotroin same time...there should be a gap of atleast 4 to 6 months... continue your daily skin care like ctms...cleanser toner moisturiser and sunscreen.. dont worry