Dont know if I will be much help but going by my HCG BT at the 4 - 5 wk mark (from last AF) I had 648 on Friday afternoon (16/7/2010) and than a whopping 1631 on Monday morning (19/7/2010). Hmm, does that help at all???
Aren't you having twins Hope?!

Three weeks Porsche - I hope that it flies for you!

Mez - I am going ok, just waiting for AF to leave the building then we can try for a sneaky BFP prior to starting IUI.....
I can't believe you are in the third trimester - my goodness time does fly! Glad ot hear all is going well.