I took Plan B approx 15 hours after I had unprotected sex- however at the time of taking it I didn't realize that my period might already be late. 2 months ago I started taking Thyroid medication and it affected my period (changed my cycle). I think (but I'm not sure) that I should have gotten my period again this week- but haven't. Last week I had severe period symptoms (cramps, moody, etc) but no bleeding. Do you think it's possible that I could be pregnant from previous protected sex (prior to 2 days ago I had never had unprotected sex) or is it possible that my thyroid medication could still be affecting my period and causing the delay? Also how long after taking Plan B can I take a pregnancy test and have it give me accurate results?