Hello, i ve been on the Essure for about two years now and my periods usually come every 28 days. I had a full period on 3/18/14 then had unprotected sex on 4/5/14, my period was due to come on the 14th had all the symptoms for it to come but it did not come until the 21st and was brownish red lighter than usual and now im having headaches, nausea, stomach pains, back pains, tiredness, but my pregnancy test said negative today, should I be worried is it to soon or no?