12dpo spotting late AF

Tara
So I know that only time will tell, but I'm driving myself crazy! 
I was supposed to get my period on CD 32 13 DPO 
I got light brown coloured spotting on 12 DPO and thought here she is. It was only there once in the afternoon. (Implantation??)
The next morning I woke up with strong period cramps and thought for sure AF would be there. 
I'm now at 15DPO CD 35 and no AF.  I've had period cramps off and on and keep running to the bathroom thinking she's arrived but nothing. 
I'm gassy, bloated and very tired.  Also waves of nausea and at the gym yesterday I saw stars when I got up from push ups. 
Took an Easy@home pregnancy test yesterday and it was negative. 
What's going on!
Should I buy a better test? Is it just too early for the easy@home ?