Implantation or light period?

I usually have 150+ day cycles and do not ovulate on my own. Well cycle days 39-42 i had very light spotting on and off And today cd43 i started spotting a bit heavier, enough that input a tampon in. A few hours later and it has stopped again. It has been mostly brown and light pink and is only when i wipe. Cd 32 i got a bfn. I am unsure if this is a very light period or if it would still be considered spotting. I'm switching back to a pantiliner and will retest in the am if the flow doesn't pick up