Hi My Last Period Ended On August 19 And And

Hi my last period ended on august 19 and and had unprotected sex the day after, it's been 10 days and last week on thursday I woke up with morning sickness but it was brief, I did not feel any other symptoms or anymore morning sickness. on friday I took a pregnancy test and it came out negative. but just yesterday on the 28th I noticed that my discharge was a light brown color but that was the only time that the discharge was that color after that it was normal again today. My expected date for my next period is on the 13-15 of september. im really worried that I might be pregnant please help with providing information to calm my anxiety.