Need some thoughts!

Kate
Just wondering what your thoughts are. I haven't gotten my BFP yet but I have been having all sorts of different symptoms that seem odd. Lots of lower pelvic cramps, back cramps, extremely tired, nausea, bad headaches that last for days, light headed, and hungry more than a week before AF was due. BDed regularly during fertile period and AF was due 12/26. On 12/26 some light bleeding started and has been abnormally light since then. I'm am only spotting today and this is not normal. Typically it is very very heavy first two days with terrible cramping - this time nothing like what it usually is. 
Is it possible to be pregnant with no positive test and light bleeding? 
Has anyone ever had this or know of someone who has had a similar experience and ended up being pregnant??
I'd love your insight!