my rollercoaster w/ NEW update

I posted a few weeks ago that I was so shocked that I had a 6 month old daughter and found out I was pregnant again, which was totally unplanned. Of course at first I was overwhelmed, but then so happy and excited. We went for our first sono today. First the tech told me I might be having twins, but she needed to do a trans-vaginal sono to really see what was going on. When she did the TV, it turned out to not be twins, but one yolk sac, and one 'fluid collection' - that they see a lot when a person is miscarrying. Then the yolk sac measured at 5weeks 1 day, which she says means I conceived around 2/7. Unfortunately, this is not possible, because we have not had intercourse since 1/28. Hearing that, she had the doctor come in to see me. He said that with all the info he was just given, he is fairly sure I am in the midst of miscarrying. I went for an HCG test today, and will be having another done on Thurs as well as a sono. He told me to think about whether I want to try and pass it naturally, or if I want a D and C.
This incredible sadness is something I've never felt before, my heart goes out to all of you who have miscarried, I had no real idea what you were going through.

UPDATE: my labs came back with a progesterone of 18 (normal 1st trimester range 11 -45) and my HCG was 14112. I had had no baseline HCG done though. Do these numbers mean anything to anyone? I know I won't know the full story until I have the next set of numbers done in two days....I feel like I won't be able to breath until then...

NEW UPDATE: EVERYTHING IS OK....I FEEL LIKE I AM LIVING A MIRACLE....as I said above, my HCG level was 14112 on monday and prog. was 18. today I called to check on my labs and they told me the prg. was 17 and the HCG was 14620. I was devastated. From everything I heard and read, if I didn't double or come very close to it, it was bad bad news. I left work crying and met my husband at home and we went for my sono. I just had my eyes closed and was praying. The sono tech, was like, 'what did you say is going on?' so I repeated the whole story. She said, well, the fluid collection is still there, but smaller, there is a yolk sac measuring 5 weeks 6 days, and I SEE A HEARTBEAT. I almost fell off of the table. My husband had actually noticed the beating right away but was afraid he was seeing things (I wasn't watching the screen). The doctor said that everyone has an HCG level where they 'top out' and plateau...and around 14000 must be mine, that it meant nothing that I didn't double (This is only bc the number was so high, if it was a low number it absolutely has to double). They still can't answer why such a descrepency (I should be measuring 7 weeks 4 days) - but he said if there was a delay in fertilization, and then a delay in implantation, that could cause somewhat of a discrepancy in the numbers. No more blood work, back in two weeks for a sono. I am floored. This has been the longest week of my life, I never thought when I walked in there today that I would be walking out feeling like I just experienced a miracle!