My 4th baby, a boy died at 37 weeks. I already had a DS and two DDs so he was going to make our family complete with two of each. I became pregnant again 9 months after he died and at the scan we decided to find out if we were having a boy or girl so I could be prepared either way.
If I was having a boy I worried he would be seen as a replacement (by me and others but mainly others) and I would forever compare, I thought if I was having a girl it would be easier but then I would always want another boy. It was so difficult to know how I felt about it all, the new baby was a boy and I cried at the scan and afterwards.
In the end, once I was used to the idea, it felt right that he was a boy. This is just me and some people will think it's wrong but I did think of both my baby boys when he was born and had cuddles. It helped me to think I was cuddling our baby who died but I never thought about our new baby as a replacement.
What I did find hard was that I compared my pregnancy at every stage, I would probably have done that if he had been a girl too but it felt constant. I agree with others about counselling and talking, there are so many issues to deal with during a pregnancy after the loss of a baby and only you know how you feel. Others can offer help but must not be allowed to dismiss how you feel, it is such a traumatic and difficult time.
I am sorry for the loss of your so and wish you a quick recovery, you must push to be classed as high-risk - your son died so you should automatically be no matter what the PM said. Our PM was similar in that there was no definite answer but likely placenta failure, I was high risk and had lots of extra care and scans so make sure you agree this with the consultant from the start.