ANSWER:
You can ask a friendly sibling or an aunt to talk to your parents and explain that you are happy with the proposal.
There’s no specific dua mentioned, just make general dua during times of acceptance, such as in salah in your sujood, in the last tashahud, before making salam, between Adhan and iqama, during the last third of the night, begging Allah until He opens the door and answers your dua.