so I was researching

About the blood gender testing and it says if you've had a reason male fetus inside you and you got pregnant back to back and they find a Y chromosome that your reasult can be wrong and it could be girl or if you have had a vanishing twin you didn't know about that was male it could be wrong?!?! Any thoughts I had a baby boy seven months ago and I got my blood test at 10 weeks and he was only five months old and I'm really convinced I'm having a girl and everyone I know thinks the same they said that Y chromosomes can stay in your blood for years and I have a one year old and seven month old and there both boys and I'm thinking the results was false I'm carrying high the baby's heart beat is 180 and I'm so sick Has anyone's blood test been wrong