My girlfriend had her period 2 times in december. she havent got her period last month or this month yet. is she pregnant? she has no morning sick

Maybe: Pregnancy is the most common cause of a missed period. If not pregnant, other causes of a late or missed period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (especially birth control pills), hormonal disorders, etc… A home urine pregnancy test is very accurate 3 weeks after sex or 1 week after missing a period.