It is possible to skip a period sometimes, maybe if your under a lot of stress or something. I would think the tests would be accurate but hey you never know ! If your really concerned and maybe having pregnancy symtoms try going into your doctor, or a clinic for a blood test or urine test from them, those are more accurate definate for sures : )

Its also possible to get 2 negs and still be pregnant. I have at least 1 friend who had 3 negatives before she got a positive. I'd go to a clinic and get a blood test.