from what i calculated I should have ovulated. is it possibe

Hey Ladys My Names Ashlie, I'm 21 my Husband and I have been trying to concieve for a few months now with no luck so a few days ago when I started noticing a change in my body I got to wondering and thought I needed a second opionion before making a trip to the Medi center... My last pierid started on the 28th of april and lasted 7days ending on the 4th of may..it usualy starts between the 28th and the 1 of every month and Ive never missed a pierod Ive never had any tipycal peroid symptoms My husband was home the 14th od may and again the 18th of may we had unprotected sex both days and then yesterday Saterday the 19th of may I went to work and came home and noticed blood when I whipped it was Bright pink and was gone with in a few hours Ive also noticed sice the night of the 14th Im sneezing alot more my back is achy and crampy and my sence of smell has increased slightly other then that I havent really notice anything. My question is Do you think I could finaly be pregnant from what Ive calculated I should have ovulated between the 13th and the 19th of may do you think it could be Implantation bleeding? if so how long sould I wait before going to the Doctors or taking a HPT?