I've been given the Ultimatum to have a baby or my partners done

My partner and I have been together 4 years, I'm 23 and he is 30 and he seems to think he's getting to old to have kids now so he's given me the ultimatum that I have a baby with him this year or were over. I'm extremely overwhelmed by this because I don't want to lose him but I don't feel ready yet for a baby. I've been trying to convince myself to do it but the more I stress over this the more I realise I'm not ready for that commitment and responsibility. My partner lives with his mum and I live with mine, I'm unemployed and I only have my Learners and I hardly have a social group too I got 2 friends that I see maybe once a month. My partner seems to think by me having a baby all this will fall into place quicker and better but I've always been the one to say we need to set ourselves up first and be comfortable before we have a baby. I feel guilty because he has been very clear about wanting a baby for a couple of years now and I always told him I wasn't ready but it's something I definitely want for our future, but this is something he wants this year or we're over. I'm so appreciate to any advice you can give