You probably need to get affidavits to prove that you have been in the U.S. since 6/15/2007.
This answer is of a general nature and should not be relied upon as final, nor is it intended as legal advice. Consult with a qualified attorney before making any legal decisions. Gen Kimura, (832) 247-6932.
You will need to search (and find) any document(s) that would bear witness to your having lived in the U.S. during that period, and if that fails (I refuse to believe it), then resort to sworn declarations by yourself, friends and family (note this is only 'Secondary" evidence and will not be as good. So, keep on searching, talk to your family, etc. - you'll find primary evidence!
Behar Intl. Counsel 619.234.5962 Kindly be advised that the answer above is only general in nature cannot be construed as legal advice, given that not enough facts are known. It is your responsibility to retain a lawyer to analyze the facts specific to your particular situation in order to give you specific advice. Specific answers will require cognizance of all pertinent facts about your case. Any answers offered on Avvo are of a general nature only, and are not meant to create an attorney-client relationship.
Did you go to the doctor before you started school? You may be able to get medical records. I suggest that you consult with an attorney before doing anything. Also, I note that you state that you entered the US in August of 2007, you need to prove that you were here since June 15, 2007.