I havent had my period in three months and had taken two pregnancy tests which were both positive. but i'm not gaining much weight. whats wrong?

See your doctor: I think you need to have pregnancy well-being checked. You will need some blood and urine testing, and an Ultrasound to check the development and the well-being of the baby. Also you might need some supplement medications to help healthy growth of the baby. I would like to advise that it is vital to have it checked. Hope all goes well with you