My menstrual came on dec.22 2017 it's due in 8 days. today is jan 12 2018 and im having light pinkish/little brownish spotting. we're ttc so i was wondering could i be getting pregnant even though i just took a test that said not pregnant

Pregnancy unlikely: 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 happened) 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 conception.