what do y'all think?

I was supposed to start my period on Oct 25th and still no sign of her!! I have taken 3 pregnancy tests and all negative. I'm so frustrated. I thought I saw what was implantation blood on Sunday (Oct 30)but it was a busy day so I didn't really pay much attention. How many days after implantation blood have any of you waited to test?? The only "symptoms" if you wanna call it that, has been major cramping in my back. Most days since the 25th I've said "oh yeah I'm definitely gonna start my period today" cause that's exactly how it feels but still nothing and all negatives. What do y'all think? I've also only used the cheap ol hpt so should I go get a better brand or something?