The meds will not destroy your organs, but you might want to speak with your doctor about your concerns. Perhaps something milder (even though that is a low dose) would work for you.
20mg is a very low dose, it cannot do any harm. I am on 150mg of anti-depressant, and some people on as much as 300mg, and others who take lots of piils of different types.
Why do you think your organs will be destroyed? Anti-depressants cannot do that. I have been depressed for 20 years, and my organs are fine. Yes weight gain can be a side effect.
I know I have to take medicine for the rest of my life. Make sure you really need to stop. I know with me, because I have tried it a couple of times, that if I stop, the depression always comes back.
You need to talk to a doctor about this. You are not harming your body in any way. Anti-depressant medication is not addictive. You cannot harm yourself with it. Why are your parents so keen for you to stop taking it?
You don't have to drop off antidepressants entirely. It might be better to switch medications. Talk to you psychiatrist about your concerns.