Hi ktfrd I'm so sorry to hear of your worries.
I have had 2 mc's- the last one happened a couple of months ago and I think my first HCG was 32 and that was 2 days after my period was due ie day 30 of my 28 day cycle.
From what i saw online, 32 is pretty low for this date, not impossible if i ovulated very late, but improbable.
(My second reading was 7, which made it pretty clear a MC was inevitable at that point although it didn't arrive for another week).
I posted in PG when i was in this position and i did get a couple of replies from people who had got very low HCG and gone on to have full and healthy PGs, so it is possible at this stage, and it is possible to bleed in early PG and for it not to be a MC...so I suppose what i'm saying is its a bit of a waiting game until your second blood test comes back, and, as someone who couldn't sleep or eat whilst waiting, i know how hard this wait can be.
(If you can't stand it, a suggestion I was given was to buy two PG test- one that picked up HCG at 20 and one at 10 and see if you get a positive on both/one/neither. If your HCG was seventeen on Monday, you would expect Both to be positive by now- i did this the morning of the second bloods result as i just couldn't stand it and got negative tests, so i pretty much knew what the test was going to find).
Good luck, i'm thinking of you.