Help!!

Soooo I get my period every month, always maybe a day early or right on it, I always have medium to heavy flow, tmi but I use tampons and I already know to change it every 3-4 hours. But me and my husband started trying for a baby this month and 3 days ago I think I started? I started spotting and I’ve been bleeding but never this light, to the point when I’m using pads because I don’t need a tampon cause it’s not heavy like always. is this normal? Has this happened to anyone?

EDIT: I did take a test like 2 days ago but negative ☹️ I don’t do birth control.