I wasn't adopted but never met my BF until I was 15. He and I met and spent time together. Then I started feeling very let down. He was not the Knight in Shining Armor that I had expected. I began to feel smothered and confused about the relationships in my life. I needed space. I did not contact him for several years after that first meeting. When I did he rejected me.
My advice is not to break contact with her (send Christmas and Birthday cards) so she doesn't feel abandon again but do not expect her to reciprocate. She needs time to sort out her feelings and see where she is.
Be open to her and not hostile if it takes her years to seek you again. Give her the same number of years that it took you to look for her. LOVE HER ENOUGH TO LET HER GO.