So sorry for your loss babe. I had a blighted ovum last summer and it still hurts. If your levels only reached 0 3 weeks ago, then it could be taking some time for your body to get back to normal. Then again, it is also possible to skip AF and still O. If it's implantation, wait about a week and take a test. If still nothing, I would call the dr just to see and ask if they have any suggestions. Good luck to you!