I'm 21years old, 30 days late, backpain, insomnia, tired and weak body, lost og appetite, and i can't focus well and struggle to remember things a lit?

Late period?: In a woman with regular periods, some causes of a late period include: excessive weight loss or weight gain, increased exercising, emotional stress, having an illness, traveling, medicines (like birth control pills), hormonal imbalances, etc… Seeing a doctor is a good idea if symptoms are persistent, recurring, or worrisome. Pregnancy is the common cause of a missed period, if sexually active.