Took some time off, back at TTC!

Long story short, my husband & I decided we would start ttc July 2013. February I had a m/c. March my cycle was all over the place... While we haven't been "actively" ttc since Feb, we haven't been preventing either. So here we are July 2014, 1 year after starting this adventure. My AF was supposed to start the 15th. I started the 11th & went thru the 18th which is very rare for me because I am a "spot on, 4 day long, consistent every time" type... Now, I am supposedly in my fertile window, taking mucinex and using preseed. If I get a BFN in Aug, do you think I should seek medical assistance? Im crossing my fingers this is the month, but I am skeptical due to it taking so long the first time... Any advice, words of wisdom, ect? Thanks ladies!!! ?