Is the questioner considered disobedient to her biological parents who abandoned her since childhood, and what is her religious duty towards them?

Firstly: Adoption does not establish lineage, nor does it prohibit what is lawful. The adoptive parents are not legal guardians (mahrams), and one must observe hijab (definition) in front of them, but their kindness should be reciprocated with kindness. Secondly: Honoring one's parents is a religious obligation, and it is not permissible to abandon or desert them, no matter how much they fall short, for Allah Almighty says: "And be dutiful to parents."