Searching for birth mother Mexico City 1972

I am searching for my biological mother. I was born in Mexico City on May 3rd 1972 to a Carmen Sanchez- Bonilla. My parents who adopted me lived and still live in Austin Texas. I know that Carmen was 30 when she had me and had 3 other children however one died before I was born. I have no information regarding my birth father. I have all my paper work however do not have any more information than this regarding Carmen. Any help or ways to go about finding her since it is an adoption through Mexico would be greatly appreciated.