This is an old post, so I am not sure if you have completed your search or not. But it did catch my eye.
Birthmothers are entitled to a photocopy of the birth certificate of a child they relinquished for adoption. You would contact the Minnesota Department of Health for this. This would help you to know the gender of your child, and the exact birth date if you do not remember. They can also tell you what adoption agency you used, if you do not remember.
Birthmothers are also entitled to a photocopy of any document they signed at the adoption agency.