I started a new birth control pill at the end of my cycle and before that i had unprotected sex. i am now over 2 weeks late for my period. but all of the tests so far have been negative. could i be pregnant or is this a side effect of the new pill

With negative: pregnancy testing, this most likely an effect of the new contraceptive. When you reach the end of the active pills, you are more likely to start a period flow, as long as you are not pregnant. Sometimes take a couple of cycles to fully regulate the cycles.

Blood test for HCG: Get a blood test for HCG level to settle the issue. Have a healthy diet, exercise 30 minutes/day, drink plenty of water, have safe sex, no tobacco alcohol weed or street drugs. For nutrition: http://www.choosemyplate.gov/. Wish you good health!