12 days late!! help?

So today I'm 12 days late, I've had implantation bleeding which occurred about a week ago, I had light pink spotting just as I wiped and then the next day was brown and that was it. 
​I had cramps from the time I was due for AF and only just stopped about a few days ago. I've taken so many pregnacy tests and all negative, I took one this morning and a BFN!! :( 
​I don't no what to do :( 
​Has anyone had this and found out later they were pregant?