Unusual pregnancy/ missed misscarrage

Hi I'm hoping I may come across maybe some who has experienced something similar to me as docters are unsure as woth nurses and friends I have spoken to. I apologize if this is long and hope I dont upset anyone but this. So here is my story around 6 weeks ago I found out I was pregnant I was around 7 weeks with yolk sac and my bloods were awesome so 14 days later I had another scan to see if there was a fetus there was with no heartbeat measuring 7.6 weeks being my 4th pregnancy I was well aware of what that meant here is where it starts to get tricky I got called into the docters and we agreed we would wait for nature if 14days later nothing happened we would book rescan so after 9 days I had 4 days worth of cramps but these stopped nothing happend I contacted docter he told me to wait till monday to see what may happen over the weekend nothing did so I took a pregnancy test as fetus hasnt had a hearbeat for nearly 4 weeks it was a strong fast positive I rang my docter to see what next I am now booked in for hcg bloods tomorrow I am at peace for whatever happens an understand this being viable is very slim I'm okay with that as I ve had a while to get my head around it what I am wondering is has anyone been in this situation and what was the outcome and also when you dont have a heartbeat but havnt miscarried what happens to hcg levels do they drop stay the same or slowly rise. Thank you