Last month I had two periods one on the 4th and another on the 15th. Uusally I am regular and start on the 15th. This month I have none so far. I have been sick with a cough. I have nausea, dizzyness, tired a lot, breat and nipples are sensitive and I took and two pregnancy test and one was negative and the other had two lines but one line was very faint. Could I be pregnant or is stress causing me to miss my period