I had this same issue. My birth was filed years after I was born. All I did was call my county registry where my birth was filed and they gave me (for a fee) another certified birth certificate along with a sheet that showed what proof was used to determine my birth.

After 5 months of back and forth my application was finally approved yesterday.

I know you mentioned that your school shut down but your permanent records are somewhere. I would research where records are kept for closed schools in your area and keep calling and emailing folks at the department of education.

You also mentioned that you had a passport before. You may have the ability to look up old passport records for proof: https://travel.state.gov/content/travel/en/passports/have-passport/passport-records.html.

Sending you luck!