marriage

I'm kind of stuck right now. My BF and I have been together for a little over 7 years. We have been together since we were 15 and about to have our third child together. We are both 22 and will be 23 later this year. Marriage has been on my mind for about 2-3 years now and my BF says we shouldn't rush it and let the time be right. I always get defensive and feel like I'm not good enough and that maybe he really doesn't love me like I love him. I don't even want a glorious wedding because I know we can't afford it right now and it's not that important. I'm perfectly fine going to a courthouse and getting married there. He tells me he loves me and he says I'm more than good enough, he just doesn't think we are ready because we are so young. He understands why I want marriage and he agrees but he feels like the timing isn't right. Is it too soon? Even though we have been together for awhile, are we still too young?