Could a blood pregnancy test be a false negative?

Hello, I am totally confused. My Fiancé and I had kind of unprotected sex on June 21st a day after my period; I am currently on NuvaRing and a blood pressure med that should not be taken if you think you may be pregnant. I mistakenly took my NuvaRing out a week early and had kind of unprotected sex a day after inserting my new ring. We did the withdrawal method but I still felt kind of weird about it so I took the morning after pill since I knew I was on the blood pressure meds and to be on the safe side. However I started having cramps like a day after and after 2 1/2 weeks of cramps and my breast being kind of painful not too sore but more less pain. So I took my nuvaring out stop taking my meds and called my OBGYN to ask how soon I could take a test to rule out pregnancy. So on July 7th they did a blood pregnancy test and it was negative less then 1% HGC they told me no way I could be pregnant start taking your meds again, however still having the symptoms so  I requested another test on July 19th and once again same negative  less then 1% HCG, I have taking a ton of HPTs all negative. So being 4 weeks since intercourse could these tests be wrong? I also had a period on July 9th a couple days after taking my ring out that was three days long one day was pretty heaving filling a super tampon once but I was also swimming so it could make it seem more then was really there. However I know being on BC can cause vaginal bleeding during early pregnancy. Any help/stories would be great, this is my first time posting! Sorry if it’s TMI.  We like to have children one day but not today we want some married time first.

[JellyBean29]

Blood tests are known to have failed, but pretty rarely.  From what you say you don't sound preggo, just sounds like to had some pretty severe period symtoms (symptoms).  But if you still feel like you could be pregnant in like a few weeks it wouldn't hurt to test again.  Good Luck with everything!

[Cherie762]

yes  if too soon I had three negatives, before a positive...was a problem with placenta not implanting properly may of been why hormone level not high enough..i almost lost son...but today he is 19 and very healthy

[Clysta]

Symptoms alone don't mean anything. They both can be a result of the Plan B. If they did an actual hCG count and it showed negative (did they tell you the actual number?) then I would say no. Numbers will not lie. Anything under 5 is negative. If you were pregnant they would be higher and they would rise.

[Cherie762]

Clysta is probably right and I remember now my false negs where urine tests...was really late when I answered sorry ! although in the world of medicine mistakes are made..tubes of blood can get lost, swaped w another patients...deffinatley test again

[fornulalavanda180]

Thanks for all you help, still testing negative as of today 8/1. The date a conception was 6/21. So still confused and worried I could be pregnant but I will find out this week, I should be getting my period on 8/6. Hope it comes to clear my mind of my fears.

[fornulalavanda180]

Yes, on both blood test the number was less then one