My 17 year old was expecting her cycle on the week of july 9 thru the 12th it now july 23 still no cycle had 3 positive pregnancy test and 2 negative and a blood hcg level of less than 1 her cycle is normally every 28. did we test too early?

HCG is produced by the placenta in pregnancy. HCG varies between 25 mIU/mL and 7500 mIU/mL during the first 5 weeks of pregnancy. It differs in each pregnancy. Home pregnancy tests will be positive on the first day of your missed period. Below 5 means that you are not pregnant. Other causes of missed period includes stress, weight gain/loss, exercise, lack of sleep.