Implantation Bleeding

Okay so, cycle day 37, longest cycle in my life. No major changes to make my average of 29-33 so long (other than sex of course with the obvious) but I started bleeding around 3pm today (Sunday 1/8/17) and I know of all places to hear other stories, it's here. I'm testing tomorrow, because while I was working today (at a stand up job) I never got my usual heavy flow, and when I went to change my pad like I usually do before bed, I wiped (duh) and literally wiped off all the blood which never happens. I'm usually fairly heavy, can never get it all gone because it's a constant flow, etc.

So who out there had a longer cycle, then implantation bleeding? Because I cramped mildly, usually it's rather painful and lasts all day the day I start, but not today. I have no other abnormal symptoms other than I've been having frequent headaches the past week (every other dayish).

Thoughts?