Blood Pregnancy tests are very accurate at 12 DPO, right?

So I thought I might be pregnant so I took a home test 10 DPO and it was negative. I went and got a blood test anyway at 12DPO and it was negative. Well now I am 15DPO and my boobs are getting sore and I am having a lot of discharge. I am also now officially late for my period. When I got the negative results I started drinking again. I never get sore boobs and now that I missed my period I am worried. I haven’t tested because I think it would be a waste since I had a negative on the blood test and hpt test. BTW I don’t want to be pregnant and I know it was irresponsible of me to start drinking again but I thought I was in the clear! So the chances that I am pregnant now are slim to none since I have a negative blood test, right?