Help!

I'm in desperate need of some help. I had unprotected sex with my boyfriend last week Saturday, 9th July. (He was far from doing anything inside of me and he pulled out long before anything happened) I was due to come on (according to my <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">period calendar</a>) on the 11th of July but I know that: 
A: I am pretty irregular 
B: I went off the pill in March 
C: I always seem to start my period on a Friday and I have no started this Friday the 15th of July either...
I'm rather concerned because I took a HPT on the 15th of July and it came out negative... But what's concerning me is that I have cramps on and off, cravings on and off, and period symptoms but no show at all. 
I will take another test next week but I'm so scared it could confirm my worst fear, can anyone relate to this or give me some advice?