Test 2 wks post-ovulation even w/PCOS?

Nina • TTC babe no. 1. Diagnosed with PCOS in Jan. M/c in June. Now trying acupuncture after several rounds of Clomid.
I ovulated on Sunday, May 4 after taking my first round of Clomid. I know you're supposed to wait to test until you've missed your expected period, but since I have PCOS I *don't* expect to have a period (at least not without taking Provera). 
​If I test on May 18 and get a negative should I consider that definitive? If not, how long should I keep testing? 
​PS- cycle buddies welcome! :)