Trolly, sympathies and congratulations - I think .
I was in similar shoes and in the end, it was FINE. My main bit of advice would be not to get ahead of yourself. Of course you now know what it means to look after a LO and having them close together is great in some respects and hellish in others.
My DS 1 and 2 are 1 year and 10 days apart. DS1 was a total nightmare, never slept (or so it seemed) and cried/screamed every waking moment that he was not on the breast. He is now 5 and still a drama queen. DS2 was my preemie, born @ 31 weeks, now aged 4 and doing fine thankfully. When I found out I was pregnant with him my main feelings were guilt that DS1 would have to be a "big brother" so soon and no longer the baby, even though he was still a baby.
The first year with them was v tough however now I am reaping the rewards: they are great friends and playmates to each other and are very entertaining.
And, we went ahaead and had DS3...
Give yourself time to adjust to this new pregnancy. The new baby will not make you love your precious first one any less. As time goes by, hopefully you will come to enjoy the thought of this new life. So, bottom line, do not be too hard on yourself for not feeling the "right" things. You feel what you feel for a reason.
As fas as having another preemie goes, it all depends what the reason for early delivery with your first DC was. Maybe discuss with your GP or obstetrician??
The very best of luck to you and your family.