Hi there I am so sorry for your loss it must be a very hard time for you right now. I had a miscarriage in 2006 in week 16 of my pregnancy I had an operation the next day to remove what was left but like you also over 2 weeks later my blood levels were still showing high pregnancy levels and I could still produce a positive pregnancy test.
I was told that I just had very high levels of the pregnancy hormone and it would get weaker over time I still suffered morning sickness for a couple of weeks after the miscarriage which was really horrible.
But some good thoughts for you I fell pregnant again and went on to have a beautiful baby girl this year, so please take some comfort in the fact that you can try again and things can work out fine it took me ages to accept that it happened for a reason and that it was not my fault. I hope all goes well for you at the hospital tommorrow x x