TTC - implantation?

I had cramps 7dpo-9dpo- kind of like period, but also had this weird quick, sharp pain on 7dpo and 10dpo. On 11dpo I started having this strange light brown discharge - only when I wiped. Today is 12dpo and I woke up this morning with a darker discharge when I wiped, but now it's completely gone. I took a hpt yesterday and this morning- it was negative. Could this be implantation? How long should I wait to take another hpt?

If I had a normal cycle (I'm very irregular due to PCOS) I could say when AF is due but I'm not sure. If it's a normal 2 weeks usually then AF would be due Wednesday if I'm right on when I ovulated.