I assume your doctor is in your plan's 'network'.
Did the visit include cervical cancer screening (pap smear or DNA test)? Have you had one in the last 3 (pap) or 5 (DNA) years? If yes and yes, it's possible that (ACA minimum rules) you are not covered. Preventative services for women that shouldn't require a co-pay:https://www.healthcare.gov/preventive-care-women/
cover more, though. Depends on your plan.
And good tips at Bedsider.ORG
:make sure to say you're scheduling a "well-woman visit"
if you were inappropriately charged a copay, contact the National Women’s Law Center’s hotline 1-866-745-5487 or via email at CoverHer@nwlc.org to let them know what’s going on and see if they can help.