Im pregnant???

Ok so i had my 2nd son almost 4 months ago on may 28th ....my husband and i talked about having more babies and that we would definitely try again soon...anyway so my period was suppose to start September 19th and when it didnt come that night i took a pregnancy test which came back negative...ok maybe glow is off by a day... i took another test in the morning and saw a vvvvvfl after 5 min but it was blue dye so i thought maybe the dye was running ...so i ran out and got a digital...anddddd there it was....it said +YES!!.....whhaaat?!?! So i went back to glow to see how this happened ....according to glow i ovualted September 5 ....and the 1 and only time we had sex was the night of September 7th...and sorry tmi but he didnt finish in me...could glow have miscalculated my ovulation day?? Well anyway we're super happy but super surprised lol we cant wait to see if we'll have a 3rd baby boy or a little girl :) i have a question for you awesome ladies ....has anyone concieved or had sex after ovulation day and gave birth to a girl???