any one rh-

I have had one son 6 and a half years ago and me and my husband have been trying for a baby for almost 2 years ... I finally got pregnant I am 4 weeks and 4 days yesterday I started to bleed really bad so I went to the hospital turns out I am rh- and they haven't figured it out after 4 lost I though I was gunna loose this one to ... But my hcg level double since yesterday so they gave me a rho gram shot ... And I have a ultrasound tomorrow ... Has any one else gone though this ? Or going though this that might be able to give me more details ... I have googled what I can but I was hoping for a little more details from someone that has maybe been though the same thing with a good out come !