possibly still pregnant???

I was due to get a period on 23rd of April and it didn't start until the 27th of April I'm always on time so this was weird ! And today I have stopped bleeding ,I already had a blood test done On Wednesday the 26th and it was negative. So should I test again tomorrow just to be sure cuz my periods are always 7days ! And the flow was not the same either . This would be my third pregnancy by the way and when me and my husband did it he did pull out but I know it's still possible to be pregnant and I have no idea when I ovulated !