1 Day and 2 Months Late

Heya Ladies!! Me again. I guess you could call this an update or call this a "worsening problem." Whichever you decide to categorize it is your decision. Beyond all this, last month I wrote about how I thought I was pregnant, but that the blood tests that my doctor's ran came out to be negative. Friday (6 April 2012), I went in again and explained to them that I had not had my period for almost two months. Again, they ran a blood pregnancy test and it came out negative so, they put me on Ortho-Tricyclene (sp?). I've only been taking the birth-control for a couple days, but now, my period is two months and one day late. =/ I've been having a bit of nausea and some spotting (about a week ago). I don't want to spark any, "Am I pregnant" questions. I'm pretty sure that TWO blood HcG tests cannot lie so, what I'm asking is: is this normal (the nausea and some spotting) birth-control side affects?? I've been under a bit of stress as of late, but nothing that I haven't been through before and do not know why my body is acting up. I've had regular periods for YEARS now... and now, I've gone over two months without a period. If nausea and (some) spotting (mainly when I wipe) aren't symptoms of the birth-control, question number two is this: is it possible for the blood HcG tests to be incorrect? Again, I don't want to think, "Oh! I might be pregnant" and me not be so. I'm being cautious and seriously doubt that I am pregnant, but I have heard of people who have gone in for pregnancy tests and they've popped negative.. and nine months later, out comes a baby girl/boy that the parents weren't ready for. Any suggestions, ladies??