Using opks with pcos.

Hi girls, needing some advice about using opks (internet cheapies) with pcos. Im currently on day 15 of my cycle and havent had a positive yet, just lines fainter than the control - every time. But on day 13 and 14 i had cramps that i get every month which i always thought was ovulation as it comes around the same time in the same area.. my question is, should i trust the opks and presume i havent ovulated or trust my own instincts about my body? Im so confused and frustrated. Ttc about 2 years and its becoming more and more heartbreaking every month 😔