There is a website which is a pregnancy planner indicator and gives the best times to have sex if you are trying to conceive. According to this chart if your period started on july 14 your most fertile day was july 27 (the day you had sex). Also, you are far more fertile after having a miscarriage. This isn't a guarantee so don't worry, but I strongly urge you to take an early pregnancy test to be sure, it is a strong possibility that you are.