It is good to hear that you have achieved good control of acne with isotretinoin. The low dose that you are taking now will reduce sebum (oil) production and maintain your condition.
From research studies done on adults, low dose isotretinoin showed no side effects to the body when the researchers did an extensive panel of blood tests on patients who took isotretinoin 20mg twice a week for 3 years.
Your dose is even lower than this so it is safe, provided that you do not have habits such as excessive alcohol intake, as that will stress your liver.
If you find that your skin condition is well maintained on this current dose, you may continue it till your late 20s when you have less oil production and acne is not a problem anymore.
