Can covid vaccines affect a woman's menstrual cycle at all? i've read some articles suggesting they do, such as affecting the timing or heaviness of the period after the shots are given, but i don't know if that is true or just anecdotal evidence?

The alleged effects of the COVID-19 vaccines on female menstrual cycles appears at this point to be anecdotal. There are many documented effects on the menstrual cycle from stress (emotional, job or school ) which can delay onset of ovulation, thereby delaying the onset of menses. The longer unopposed estrogen from delay of ovulation lasts, the heavier eventual bleeding is.

Agree with Dr. Berryman. Reports appear to be largely anecdotal at this point. See: https://www.health.com/condition/infectious-diseases/coronavirus/can-covid-vaccine-affect-my-period