It's only been 8 days since you said you were supposed to ovulate, you could have ovulated later or a little earlier. It's too early to be testing. It's always best to wait until the day your period is due or until it is late to test, the longer you wait the more accurate the test will be, because it can take 6-12 days for a fertilized egg to implant, and another 2-4 for the HCG to be high enough to show positive on a pregnancy test.
It could be that you have tested too early, if you've tested before AF is due then you could be pregnant and not have enough HCG in you for the test to pick it up. Wait a few more days then test again.
im same as you TTC with 2nd, ovulated on 3rd Aug, tested on 13th, 14 and today and still neg. Had sex right around ovulation as well so still hopful i am and that i just tested too early. Just going to grit my teeth and wait until 17th for expected AF.
You should prob wait until your AF date as well as testing too early can give false neg and confuse you even more.
If you ovulated on 7th, it would on average implant after 7 days, then HCG doubles every 48-72hrs, so at earliest you could prob test 20th.
Best of luck to you.