Engagement panic

My boyfriend proposed exactly a year into us dating and said he wanted to do it sooner

I told him I wanted to wait, at least another year, like how can I agree to marry you until we've learned more of each other?

But then I start panicking about what if he asks again and I still don't feel ready to make that commitment? I don't want to say yes and then for some reason we not only break up but break an engagement?

It just seems like so much, I still consider myself pretty young, and don't even have a stable home which is what I want even more than marriage