Can Caffeine And Diarrhoea Affect Blood Serum Quantitative Level?

My date of LMP was October 27th. On November 18th i had a positive home pregnancy test which i took in the early evening and was not even a first morning urine. This was about a week after ovulation and the only possible dates of conception. I saw an OB early due to a history of insulin dep. GD. At the meeting i told the Dr. i have very early symptoms, tested very early and felt more pregnant For dating purposes due to the GD and the confusion about symptoms he ordered an US the following week on the 8th. At the us, they saw a sack, no fetal pole, that measured a week younger, so about 5 weeks, then the expected 6 weeks. He suggested that i might have ovulated later but that wasn t really possible due to the very early positive on the hpt. He sent me for a blood serum quantitative and i had a first draw that same afternoon, the 8th. The first level was 17500 and this surprised the Dr. The second draw on the 11th showed a level of 24900. Not a doubling. So here is my question. I have read that diuretics can lower, slow and plateau HCG levels. I am a regular caffeine drinker and further, i have had diarrhea for weeks since finding out i was pregnant. On the day of the first draw, i had been drinking large amounts of water and for hours in anticipation of the u/s. Could the caffeine and diarrhea, without the extra water consumption, have affected my second set of numbers? I hope this is all written clearly and i appreciate any input. shannon