Had unprotected sex 3/24, no ejaculation just pre cum, took plan b pill hour after sex, vaginal discharge 3/29, what are the chances that im pregnant?

Slim to none: With all that you described, it would be very very rare for you to get pregnant from that encounter. But next time, use birth control and condoms. Best wishes.

Always possible: Anytime there is sexual intercourse , and especially when there any ejaculation in the vaginal , there is a chance of becoming pregnant. How high? Hard to tell you that, but if you want to avoid pregnancy then there is only one sure way: abstinence. Take a test if you are more than 2 weeks late for your next cycle.