3 days late and scared to take pregnancy test

Zilla
I was 3 days late and then I started to have a pinkish, brownish waterish discharge. I am not sure if I started my period as it is way less flow than normal. Also no cramps-and I usually have period pains. I also had a mild migraine, and people told me it can be progesterone levels spiking, but I got migraines before when it was my period.
Someone told me of "inplant bleeding"...I do not know whether this is inplant bleeding or my period. I am so scared to take a pregnancy test and get a negative.
I have a docters appointment tomorrow...