How do I tell my parents I want to marry him?

Assalamu Alaykum sisters. I really have been deep into my thoughts and have been in a huge amount of stress, and I'm in desperate need for advice. For 2 years I have been sinning. Everyone sins, but I knew what I was doing is wrong, I just avoided it and let my feelings overpower and change me. I met a Muslim man at my sisters wedding when I was in the hallway on my way to the restroom. He asked me questions in hopes to know me better.. We didn't have enough time to know eachother more.. And we exchanged numbers. We would text and he told me ASAP! I want to ask for your hand NOW. I wanted to tell him yes, but an issue has happened with my brother, and my mom is focused on getting him married. My mother forgets about me and doesn't really worry or think of my desires. I'm also a Senior in highschool and I know that my parents will not open the discussion for marriage until I finish my senior year and hit 18. I told him when I finish school I will tell them, and everyday is harder because I see how worried my mother is about my brother and little does she know is she should be worried that I'm taking marriage in my own hands and because of that, I'm doinf haram and sins... I just want to tell them and ts killing me. I would try to tell him we can speak when j finish school bur he would always end up speaking to me.. Because he misses me. I know in Islam it's not haram to love a person, and want to marry him.. But it's haram what you do with that love. Him and I were sinninf for 2 years because of temptation.. And we avoided the fact fhat we knew it was haram. Sometimes we would take a long break because we realized how we started to forget Allah, because we were so into eachother. Recently hes watched a video on how to fully repent and it opened his eyes and he told me we cannot speak anymore. He said when I'm ready to tell my parents he will ask for my hand in marriage right away. He wants to fully repent and be close to Allah, and he shared the video with me and Although I felt sad we will not speak anymore, I'm happy because I can focus on my Creator.. i can impfove myself as a muslim.. Ask for forgiveness.. No distractions.. i want to be a better muslim. Alhamdulilah we both have decided on this and in sha Allah ya rabb.. In sha Allah we are forgiven. We still have intentions marrying eachother, but now I'm afraid of telling my parents about him. I feel confident because I know he does fit the descripton of a good muslim, The only thing thats made him weak is being with me, because it kept him away from Allah bas alhamdulilah hes changing that.. In our relationship he gave me more knowledge on Islam, things I didnt know before, and I know that if we marry, we can benefit eachother islamically. He's very smart, and has a job and in college to he a pharmacist alhamdulilah. The one issue is that he's yemeni and I'm palestinian.. My parents are very strict on our culture, and expects for me to marry a man from my country in my village. I know I have no right to judge what theyre doing if its haram or not because I've done things that are haram and I'm fully aware of it. But I now realize it thanks to that beautiful video, and I want to marry him the right way. I'm waiting 5 months until I graduate, and I plan on using my time focusing on Allah and my prayer and reading Quran and gain more knowledge in Islam.. And ask for forgiveness. But please, how can I adress my parents? It is haram for them to reject him just because he's of a different culture... His culture is similar to mine.. And the way of islam is how we live by. That's how we SHOULD think of it. Why limit ourselves when there can be a Muslim man that fits the description for marriage? Please help.