anyone had BFN and after a few days positives?

I've had 4 BFNs and I'm 2 weeks late, I'm on the pill I know this is stupid to ask, but I have family history where they have gotten pregnant while on the pill.
It's been 6 months since I started the pill, never missed a period until now, I had spotting one week before my period but it was really light, I could tell cause the toilet paper was different color, but never got in my underwear so I could tell it was almost nothing 
Been feeling nauseous since 3 days ago, bloated and lower back pain, since I started the pill never got the pinching cramps which I had when I ovulated and now I have been feeling it since last week, they come and go right away.
Since I tested and it was negative I was wondering if any of you guys had any positives after? And how many days should I wait to test again?