Dating

I'm 18, I've been dating a guy for like 8 months. Before we even dated, I knew him for like 5 years. This Novemeber will mark 6 years since we met. He was my best friend for a very long time before we dated, and remains my best friend while we've been dating. I'm completely in love with him, and I've honestly never been happier in my entire life. I'm 18, and he's 22. The age doesn't bother me, never has. We dated before I turned 18 but my parents gave us permission and they love him. We've talked about what we think our futures would be like, and the topic of marriage came up. He said he would like to marry me. I told him we should wait a little before getting engaged, but I'm totally 100% sure I'm not gonna want anyone else. He makes me happier than anything on earth and we've been through hell together. I honestly can't imagine my future without him. What made me wanna wait was because I don't want to disappoint my parents. I know everyone would think I'm "throwing my life away". I already know I don't want to get married until I'm atleast 21 (I made the joke that if I'm gonna be faced with the fact that I'm tied to him forever, I wanna be able to drink legally lol completely kidding) and I think I'm making the right decision on waiting a little while before getting engaged (I know he isn't going anywhere, I'm certainly not going anywhere, the waiting is mainly so I can get my dads blessing to do so). What advice do you guys have? (Sorry it's a such a long post lol)