What are the chances for a false positive at the doctor's office?

[mahal7_8]

Hi and please give me your feedback.
For the past few weeks I have been feeling more tired than usual. On one or two occasions I felt nauseated and dizzy. I am very irregular and haven't ovulated on my own since last year. I took Provera twice this year to bring on my period. My last period was in April.
I went to the doctor last tuesday because I strongly believed I had a urinary tract infection because I felt some burning when I pee sometimes. Nowadays I haven't had any burning at all.
I happened to mention to the doctor about my irregular menses to ask her for Provera and she decided to test my urine for pregnancy. She came back in less than two minutes and said no which I knew was going to happen. Me and my husband have been trying for baby #2 since january 2013 but since I knew I had not ovulated I wasn't expecting to be pregnant at all.
Just as I was about to leave the doctor's office, the nurse ran after me and told me to come back. Then the doctor tells me the test turned positive. She said it was faint and that false positives never happen. I was in shock and disbelief but I knew false positives do happen.
Two days later I tested at home with a First Response Early Detection test and it turned out negative.
What are my chances of getting a false positive at the doctor's clinic?
I am going back to see the doctor but probably won't be until next week because they are always fully booked.
The doctor scheduled me for an ultrasound to determine how far along I am but I don't want to cause any embarrassment and disappointed for myself if I am not pregnant. I also remember the doctor told me I had a little protein in my urine. Will this cause a false positive?
I have cried my eyes out already and have accepted that I am probably not pregnant because I just don't feel pregnant. When I was pregnant with my son I had so many symptoms and the First Response showed dark positives.
Please give me your opinions. I have learned to accept that I may not be pregnant.
I Googled my situation like crazy but have not found much info about false positives at the doctor's office.

[wickedxchick]

Try another brand. I used first response and it said negative. A faint positive can mean you are very early in your pregnancy, that's how mine looked so I kind of doubt if I really was pregnant a few days later I retested and it was brighter

[cindy82]

Like they said they should have done a blood test then.false positives are really rare, I wonder if she read it within the time frame she was suppose to.

[MandynShane]

If I were you, I would request a blood test. Its a definite yes or no...100%. My husband and I had been trying for baby number 3 since september 2012, and I am now 7 weeks. One test was positive,  and one was negative. So my doctor ordered a blood test.

Good luck!

[Kate037]

I have never heard of a false positive from the doctor. If they weren't sure they would have either let you go or made you retest. That being said, doctors tests are a lot more sensitive then at home tests, this is my second pregnancy and I've never had a positive home test. If you doubt it that much maybe you should go to a different doctor to confirm. Good luck (and congratulations!)