Anxiously waiting...

Hello! My fiancé and I have decided to try to conceive, our daughter is 4yrs and we don't want them too far apart :) I've been lazy with keeping up with AF previously but I downloaded Ovia fertility app and started with my current start date( 9/8). The app said my ovulation period was between (9/21-26) given the 28 cycle, which really I have no idea. So I figured it was a good start date to start trying. Well for that whole week plus weekend my fiancé and I got busy, in hopes that we were making a baby! Now I took a pregnancy test this morning and it showed negative. This is 6-7 days from my start date. I used First response. I think about this every second of the day. When should I test again? I want to know like yesterday. Have any of you gotten a negative reading and then a day or two later gotten a positive??? With my first I didn't have this waiting game problem, she was a beautiful surprise!