Post-Miscarriage Symptoms: Could This Be a New Pregnancy?

Question
Age 33, one child age 6.  On 2/19/04 I had a miscarriage.  I am now 2 months post miscarriage and 2 weeks ago my Dr. did a quantitative and my HCG was less than 5 so he told me I was now clear of miscarriage.  Approx. 1 week ago began to feel new pregnancy symptoms.  I have had many faint positive hpt, none that are really dark, but all of the tests have come out positive.  Went to the Dr. last week Thursday and did another quantitative, which he told me was still at 0.  First question is:  Is it possible to become pregnant once again so soon after miscarriage without a period?  Second question is:  Is it possible that the previous pregnancy is registering on these hpt giving me positive results, although my quants were at 0 two weeks ago?  Lastly, could it take a week or so for my blood quants to show positive if this was a new pregnancy since I'm only getting a faint positive on the hpts and the Dr. said I'm still less than 5?  My doctor said that he has heard of cases of blood quants not registering immediately, but I have not.  Any help you can provide would be appreciated.

Answer
If the Beta HCG results are less than 5, it is unlikely that you are pregnant, in spite of a faintly positive urine pregnancy test. The manufacturer claims that unless the lines are dark and bold, the test must be considered negative. Did you get a period since the miscarriage? If you did, it would be easier to tell when to do a pregnancy test. The best time to perform a pregnancy test is 21 days after the suspected day of conception. HOwever, although there have been some reports of false negative blood pregnancy tests, the vast majority of Beta HCG tests that give a value of less than 5 are accurate.