Pregnancy or AF symptoms?

My husband and I have been TTC for a year now, and this month I just feel different than I have in past months. I am 13 dpo today, and yesterday I started spotting some. It was a faint pink and I only noticed it when I wiped and today it is a dark brown, but only there when I wipe. The past week or so I have not been cramping, but it's been more like a soreness or stretching kind of feeling and yesterday I was feeling a sort of sharp pain in my lower, lower, left abdomen. I've also been having trouble falling asleep at night even though I'm so tired, and have been sleeping 8+ hours or napping throughout the day because it is like I can't get enough sleep. I have also had really bad acid reflux the past few days, but I don't know if that is even a symptom of pregnancy. I took a hpt yesterday, but got a BFN. I'm wondering if what I'm feeling would be symptoms of pregnancy or if I'm just convincing myself that in my head.