Frustrated

Help?     So when exactly do you ovulate how do you count the first day of your cycle?     I just bought different ovulation test because last week I tested all week and didn't get a positive my doctor begs to differ because we checked my progesterone and it looks like I did the way I'm counting we would of had sex everyother day that week but I'm worrie do missed my fertile week! UGH I need to just have sex for 1 month everyother day but as crazy as it is it's so hard to do with our schedules!   We are 1-2x a week or sometimes not even that!