I had a period feb 28th until about march 4, I had sex on march 8th i didn't have sex again til march 23,24,27,28,29 most of the time using condoms but never ejaculating inside me well i didn't get a period in March it was due march 28th. I took a pregnancy test April 6,7 negative. I started spotting bleeding april 17,18 for a couple days which i thought was a period but my doctor said it was implanation bleeding. May comes no period tested again May 22 its positive. I went to the doctor June 5 which they did a ultra sound it came out 12 weeks 3 days minus the 2 weeks its 10 weeks 3 days. She give me a due date of dec 15 conception date March 24th but i can recall using protection but not completely sure but this would mean i ovulated late? is this correct and i can be sure i didn't get pregnant march 8?