can i be pregnant?

hello everyone I have a 2 year old son who came as a huge surprise didn't know I was even pregnant because I still got my period light for couple of days come to find out I was 2 weeks.... now recently me and my hubby who I've been together for 8 years wanted to try for another...we had sex twice after my ovulation day..and Skip a day and had sex again and one more time before my expected period and all he has ejaculated inside...I started feeling weird as the says went I took two pregnancy test n they were negative.. don't know if I should see my obgyn just yet or just wait because air my first child when I tryed a pregnancy test it was negative so I had to check my blood test