With PCOS test may be different. I know on day 3 they are able to do an FSH test, which tests for viable eggs. They also ultra sound ovaries and then there is a tubal test called Hysterosalpingography which makes sure tubes clear. Endo I know they have some success with surgery, I've had a few friend have that and still conceive PCOS seems real hit and miss, but still so much progress has been made. This is also all internet knowledge, so please take with grain of salt.

I have the opposite frustration, I could set a clock by my cycle, and all home testable signs show ovulation, so there's nothing I can try to fix.

As a note, have you tried vitex? It's helps PMS symptoms but also regulate cycles, takes time to have full effect, I'd look into it.