Could we still get a positive??

This is my husband and I’s first month TTC. I’ve taken home tests and did a blood test at the drs yesterday but all were negative. Even the doctor said though with all of my symptoms it sounds very much like I’m pregnant. I have no idea why else I’d be feeling like this for the past few weeks but she advised me to keep testing up until I get my period. I’m 12 DPO currently. Is it possible that the blood test was too early or in this time frame do you think something would have shown up if I was pregnant?