I have not have my period as yet. nausea, lower back pain, light headaches, breast is tender and sore. i have done 2 pregnancy tests but one around 9am and one at 12 two different days. both showed negative. what must i do what cab it be?

Tests are accurate: Today's home pregnancy tests are very accurate and not affected by foods, herbs, common illnesses, sexually transmitted diseases, vaginal spotting, or medications. A test gives a reliable result 3 weeks after sex (3 weeks after when conception might have been) or 1 week after missing a period. If done sooner, a negative result may be due to testing too early, such as less than 2 weeks after sex.

See below: If you had sex since you last period, do another test in 4-5 days, unless you get a period by then. Use first morning urine and follow the instructions carefully. Alternatively you may get a blood test for HCG level if you have missed your period by more than one day. Wish you good health!