Chemical pregnancy ? Help

Horrocks
14dpo today. I've had light pink/brown spotting since 12dpo. Not enough to wear a tampon or panty liner. Its only barely there when I wipe. No cramps or sore boobs like I usually get before AF. Only twinges or pulling around my lower abdomen and ovaries. I'm really worried about my test being so light. Ttc for almost 3 years. And also my lower back has been very achey for about a week. I'm due for AF tomorrow. Idk if I implanted late or what. I'm just very nervous.