Should I keep testing!?

Marissa

So I tested Saturday when I was 7dpo and got a very fain positive ok a first response test, and tested Monday morning at 9dpo and got a faint positive. I went in for a blood test Monday and got results today and the blood test came back negative? I have a history of reoccurring miscarriages at 4-5 weeks along hence why I am testing so early. My breasts are SO SORE! I can't lay on them, hardly wear a bra and I feel nauseous all the time! Could the blood test be wrong?