I had the same problem three months ago. I was a month and a half late and I took three home pregnance tests and also went to the doctor and did a blood test all came out negative. I started my period the day that I came home from the doctors visit. I think it was stress among other things. Just try not to think about it and it will finally show up.
Because you had a pregnancy blood test performed, then this does rule out any chance of pregnancy. The blood test is 100% accurate and measures the exact amount of HCG in your blood so this rules out pregnancy completely hun. If you're period doesn't arrive in 2 weeks then return to your Doctor for a Quantitative beta hcg pregnancy blood test. You'll need to ask specifically for this blood test. Take care.