No show for AF. Any advice

I am 7 days late. With sore boobs, headaches and slight period like cramps.  I have a very regular 29/30dat cycle. TTC for some time with no luck! All HPTs that i have taken have been neg. Doc has told me to wait another week before doing anything. 
Started having worse period cramps but still so AF show. Desperately want a baby. Is it possible that I'm getting a false negative or could I just be stressing myself out which is stopping AF!? 
Please any advice would be great