Understanding Pregnancy Test Accuracy & Symptoms After Emergency Contraception

Question
I am 34 years old and have no childern.  I had one pregnancy that did not go to term when I was 18.   I had my last normal period on Feb 16. I had taken plan B on March 7 due to condom faliure on March 5. On March 16 I bleed for 2 1/2 days. Started taking new brand of birth control pills. Started to have sore breasts and some nausea. Being a little scared due to the the symptoms I went to the dr and took a blood test on March 23.  They said I was not pregnant they did not give me a number just that the test was negative.  I bleed again on April 13 for 2 1/2 days. I took several home pregnancy tests all negative. Not feeling right I stopped taking the brith control pills (I have not had sex of any sorts since the March 5 incident)I went to the dr again on april 21.  I took a urine test at the drs office and that was negative.  I aslo had a pelvic exam and asked the dr if I was pregnant and she said not.  She said to put my mind at easy that she was going to do a blood test that test came back negative with a level of less than 5.  That would have put me at 9 weeks. I then bleed again on May 8 for 2 1/2 days. My stomach feels very bloated I have not gained any weight but out of fear I took a first response test yesterday and it was negative as well.
My questions are as follows...
Is a blood pregnancy test accurate when it was done I would have been 9 weeks.
Can a dr tell if I was pregnant by a pelvic at 9 weeks?
Would a HPT show up postivie through out pregnancy?  I called the first response number and they said yes but just want to double check.
I keep reading these stories of women who get their periods and negative test and still end up pregnant. How common is that?

Thank you in advance for answering my questions

Answer
Lynn,
I think you can be sure that you aren't pregnant at this point.  First of all, you are right in thinking that home pregnancy tests can give you false negatives, however, the blood test is extremely accurate, especially since it has been repeated in this case.  Also, a pelvic exam at 9 weeks pregnant would reveal an enlarged uterus.  It isn't very often that people get there periods and have negative pregnancy tests when they are really pregnant.  I hope this helps!  Good luck.