Not mature enough to get married?

Asalamualaikum. I am a 19 year old girl in uni and me and this 19 year old boy in my uni both like each other. We have talked to each other briefly and immediately discussed marriage because we want to keep things halal.

We both want him to talk to my dad formally and get things going, but obviously marriage is going to have to wait until after we both graduate college.

However, I do not feel like I am emotionally or mentally mature enough to get married until a few years after I graduate college. I want to be able to live my life to a certain extent before settling down and getting married.

How do we go about pursuing an eventual marriage when we don’t feel like we are able to take on the commitment of marriage just yet? JazakAllah Khair.