Possibly pregnant?

Hi ladies I have searched the internet but can't really find much. So I stuffed up my pill a few times accidentally and I ended up having 2 periods in one month then it was time for my period again so I stopped taking the pill but my period didn't come I did 2 at home pregnancy tests 3 weeks ago all negative after still not having a period I had a blood test and that was negative. It's now 2 weeks after the blood test and still no period I haven't been taking the pill for about 3 and a half weeks. Iv noticed for the last few days Iv got sore nipples. Could it have been even to early to get the blood test done? Has anyone had a negative blood test and still been pregnant??