I am 6 weeks pregnant and small sac gestational?

Not enough info: Unless the exact date of ovulation is known, one ultrasound should not provide a prognosis. Also, the sac in the uterus needs to be confirmed gestational as opposed to an ectopic pregnancy. At a true 6 weeks gestation, the sac should also show a yolk sac, fetal pole and cardiac motion. But your dates may not be accurate so recommend follow up ultrasound to evaluate growth.