Partner problems

So am 5 weeks pregnant and me and my partner had planned to have a baby we are both 20 and we both have a job and I already have a son... he's been abit off it for the past few days so I asked him if everything was okay and he just comes out with that he doesn't know if he's ready.... he does overthink things a lot.. he says he is worried about money, house and how our relationship is going to change when the baby comes and if he will love the baby like he should.. I just don't know what to do because I feel for him and want him to be happy but at the same time am thinking we'll can't you just put it to the back of your mind and just act excited! I just need some advice and help...