Birth Sister, born in the mid 70's, Medford Mass.

Hi, I am looking for my older half sister. She was born in the mid 70's, I was born in 79, and she is 3-5 years older than me. My father relinquished his rights during a step parent adoption when my sister was 3/5 years old. Her first name begins with K, and I am pretty sure her name is Kathleen, or Katherine, and she kept that name after the adoption. I am also not sure if she even knows she is adopted. My fathers first name is Tom, or Thomas. Thanks for looking. Lisa