how long can implantation bleeding last

mads

i’ve had brown discharge for exactly 12 days now. is there anyway that this could be implantation bleeding? it’s been mostly a dark brown with jelly texture strings of brown. no red, no cramps, no tender breasts. i had a migraine for one single night and that was before it had started. i just started BC sugar pills on the 1st and i’m now waiting for my period to hopefully start but i’m just confused as to why i’ve had the brown for so long since implantation bleeding is usually light and short.