Took plan b 2 months ago, started what i think is my period today (not on cycle). the blood is bright red but watery. is this normal?

Irregular period: Plan B effects you for a couple of days after and would have no effect at al on bleeding two months later. If you feel your bleeding is abnormal schedule a visit with an obgyn to discuss the many options available for cycle control

Maybe: Plan B is suppose to prevent implantation. Have you had a period since you took it? If not, this could well be a miscarriage because the Plan B didn't prevent the pregnancy but did enough to lead to a miscarriage. If the bleeding becomes very heavy and you are passing clots or if it lasts more than 7 days you need to see a doctor.