Parents Are Blocking My Nikkah Despite My Engagement

Assalamu Alaikum, everyone. I’m feeling lost and need some advice. I’m engaged to a wonderful man, and our families really like each other-my parents adore him, and his parents are fond of me too. His side is okay with us doing the nikkah next year, inshaAllah. Even though it’s a bit of a wait, we’re willing to be patient to honor their wishes. But my parents are completely against it. They insist I wait four years until he finishes residency-he just started medical school-and only then can we have our nikkah. My mom called me selfish because I said I want a tiny, simple nikkah at home, but she’s dreaming of a huge venue with loads of guests. My husband-to-be and I don’t want to risk falling into haram, and I tried explaining how we want to make things halal, but my parents refuse to listen. I’m not even sure what I need to do to get the nikkah done, and if it’s required to have my father as my wali. For context, we’re both Hanafi Sunni, so what can we do that’s completely Islamically allowed? I worry that if we stay just engaged for four years, we might end up sinning.