Period and still pregnant???

Since coming off Birth Control probably 2 or 3 months ago, my cycles have been around 23 days long. When my period was due this month I had none of the normal symptoms for me, no cramping, no sore breast etc. When my period was 3 or 4 days late my breast finally started to feel tender, and i had some mild cramping but nothing bad. I did get my period on the 4th, making me 6 or 7 days late, and it lasted about 4 days but was a lot lighter then normal. For the last 4 days i've had bad headaches, no appitite at all and when I do eat i feel sick, exhausted, diarrhea one day and constipated another(tmi, sorry!!) etc and have been urinating more, 2-3 times an hour sometimes (but i've also been drinking a lot of water to stay hydrated). Also, i've been feeling light headed off and on.
Has anybody had what they thought was their normal period and still been pregnant or am I just being paranoid? I haven't taken a test yet, but will if I dont start to feel better in a few days.