Doubts over second child

Please can someone just offer me some sound advice. I’ve known for about 2 weeks now that I’m pregnant again (guessing from LMP I’d be around 6 weeks, this is my second pregnancy) my 2.5 year old is great and we’ve had a really solid good time of it with her this far (though looking back now if I was completely honest with myself I think I did suffer with PND and just wouldn’t admit it to myself or anyone round me) but I can’t feel happy or excited at all this time round. It was a shock first time round but once the shock wore off I was delighted and so ready to be pregnant and become a mum but this time all I’ve done is cry and feel like I don’t even want this baby (I’m not even sure I do, my husband and I have spoken about another one but was never planned). I just feel so lost, I don’t know what the right or wrong thing to do is. Will I start to get excited as time goes on? My fear is I let this pregnancy continue and still feel the same in 9 months time, I’m not sure I am strong enough to cope mentally post-partum.