Alright! I have a question!

So... my last menstrual period was the 3rd to the 6th and my husband and i did our thing on the 10th and 13th and twice on the 17th and once on the 18th, well on Thursday the 28th I got a positive on a pregnancy test, my question is how is that possible when it hadn't been 2 weeks after my ovulation?? O.o it might seem like a stupid question but im actually really wondering lol