No Af but no bfp

Megan
Yesterday I was sure Af was going to come on as I was getting cramps but nothing. I'm two days late, I'm usually very regular witha 28-29 day cycle.
I think I ov'd on the 12th but don't use opk just going by my cm.
​ 
 I tested on Wednesday dpo 10 with Frer got bfn. Tested yesterday with a cheap test got an invalid result tested this morning with another cheap test got another invalid.
​Don't have anymore tests in the house can't get any more til this afternoon.  Just want Af to show as I really don't think I'm pregnant as yesterday cramps were abit painful.
 Mother Nature is a bitch