Boyfriend withdrew "pulled out" before he ejaculated inside me. The day after I took plan B. I have PCOS. What are the chances of getting pregnant?

Good choices. Withdrawal is not an effective for of birth control. In fact it is a good way to become pregnant. Using Plan B reduces the risk of pregnancy but is not as effective as an oral contraceptive. Always use a condom to protect against STDs.
Very low. Plan B One-Step is up to 89 % effective when taken within 72 hours (3 days) after unprotected sex. It can reduce chance of pregnancy by up to 95% if used within 24 hours. It continues to reduce the risk of pregnancy up to 120 hours (5 days) after unprotected sex, but is less effective as time passes. Withdrawal is very ineffective as birth control.