I am also Rh Neg & althjough I know there have been many replies already to this, just had to drop you a line as I know only too well how serious a situation this can be and also how worrying. But first of all try not to panic too much but get ready to educate yourself, especially if you do develop rhesus antibodies...which may not have happened anyway if your miscarriage was before 12 weeks. In this day and age Rhesus Iso Immunisation should not happen as the anti d you recieve via injection in the latter of your pregnancy should stop this happening. However, this is not always the case (as I know only too well) so I think you are right to be cautious but not stressed at this satge.
If blood tests show you do not have Rh antibodies in your blood then your pregnancy should progress as normal just with a few extra blood tests and Anti-D shots. The risk arises when antibodies are detected and if this happens you need to be pretty well educated on the subject as you will find that most midwives and GPs have very limited knowledge and understanding of the subject. If you develop antibodies (which will show via the blood tests)my advice is to then request to have all of your ante-natal care via the hospital under supervision of a consultant who has experience in Rhesus Iso Immunisation. Believe me, when it comes to the NHS and this subject you have to be pretty anal.
I myself am Rh Neg, my husband Rh Pos. I have been through three pregnancies with Rh antibodies, the last one resulted in my child being born with Haemolytic disease and requiring a blood transfusion, phototherapy & a lengthy stay in special care. However, I was lucky enough (in my final pregnancy)to have a superb consultant and had educated myself to the latter on the subject. One comforting fact is that even if your baby is born with severe Haemolytic disease (as mine was) there is a strict course of treatment that is followed which altough very traumatic does work. There are also treatments that can closely monitor and, if necessarry, treat affected babies whilst in the womb. Finding good quality information on the subject is sometimes difficult but it is comforting to see that more and more people are sharing their experiences and it is becoming quite apparent that this is something that is still a serious complication of pregnmancy and one that needs to be dealt with appropriately.
My advice really is to LEARN as much as you can and as ASSERTIVE as you need to be in ensuring you recieve the appropriate care for you and your little one/s!