My period is one week early, it's light and pink i also have nausea and a headache could i be pregnant? my last period started 26/12/15

Hard to guess: It can be hard to tell if a woman is pregnant because some of the symptoms seen in early pregnancy can also happen in non-pregnant women. A urine pregnancy test gives a reliable result if done correctly. One can test about 3 weeks after sex (3 weeks after when conception might have occurred), or 1 week after missing a period. An Ob-Gyn doctor can evaluate any persistent or worrisome symptoms.