I have PCOS. My AF was always the same. 2-3 days of light bleeding followed by spotting for up to a week. I haven't had AF since DD was born. My cycle was irregular often over 90days. While TTC, I took metformin as prescribed by my dr along with a low GI diet (I wasn't overly strict on that though) and that regulated my to around 35 - 45 days give or take. I never had any reason to suspect that I might be pg as I never POAS prior to AF being due as I never really knew when it was due IYKWIM. I did have one AF that was much heavier while TTC DD & I did wonder if maybe it was a M/C but since I didn't have any reason to consider the possibility of being pg, I chose to believe it was just a random heavy cycle. I never had any pg symptoms early on for either pregnancy.

The ache you described sounds like it could be ovulation. I felt dull pains on one side sometimes and it corresponded with when I "should" have ovulated based on when AF arrived. I have heard that some people can bleed a little as a result of ovulation. It didn't happen to me personally though. What is the discharge like? If it's a similar consistency to egg-white (EWCM) and really stretchy, it can be a sign of ovulation. (Sorry if you know all this already).

HTH