Is what the questioner did – in terms of his conversation with the girl’s father, and his agreement with him to propose after completing her studies, with the family’s knowledge, and with the girl being non-Muslim who embraced Islam and maintained her hijab – sufficient to please Allah the Almighty?

You both did well by distancing yourselves from what displeases Allah. Repentance is obligatory for every sin and has conditions: desisting from the disobedience, regretting having committed it, and resolving never to return to it. If you think that your conversation with the girl's father justifies your continued communication with her, then your communication with her is unlawful until the legal marriage contract is concluded. It is obligatory to cut off this communication and be patient until Allah facilitates your marriage. Do not be content with what has become apparent to you about her situation; rather, ask trustworthy people who know her about her.