help! what other documents to prove i was here before 16?

So, the only hard copy i have is vaccination record but that is dater 8 DAYS after my 16 birthday and after reading some stuff cant have an affidavit for that. any other ideas? i also have pictures but none are dated therefore cant prove i was 15

another question, can i use an affidavit to validate the year of a picture? you know like the person who is also in the picture can confirm the day/year?

Do you have any school records?