Late period after chemical pregnancy

Hello all,
​I had a chemical pregnancy last month. Started to bleed on August 15th and ended august 19th. According to what I read online, that counted as my regular period (unless I am wrong) so my next period was scheduled for September 15th. I took 3 pregnancy tests and they are all negative. Is it too early to test? Am I just running late? What is going on?!?! I am so confused!!!!! 
​I really want it to be too early to test but at this point I'm not sure