Hi AmalieJasmine,
I am so sorry that you are having so much pain!
Birth control pills contain estrogen and/or progestin which could cause you to experience poor lubrication, dryness, and inflammation of the vagina, which may then lead to dyspareunia (painful intercourse). That pain can cause the vaginal muscles to spasm causing a tightness as well.
You may need a hormonal cream to help repair the vaginal skin and then dilation to help return the vaginal muscles to their normal state. I would recommend making an appointment with a provider experienced in vaginismus/dyspareunia to help with this. But the pain is treatable. And they should be able to answer your questions about PCOS too!