American F4 visa is over age.

Your name in the interview letter does not necessarily prove that you are not over age.

Immigrants like you, 2 1 year old, unmarried is the basic condition. If you are over age, you have to reschedule.

But the United States has a child protection law, which is to help the children of immigrants who are over age after a long wait.

Whether you meet that requirement depends on some details of your application, which is not easy to discuss here.

I suggest you consult your elder sister-in-law with an American immigration lawyer.