Can someone help me please?

Ive been on soy iso's and i finally started my period after a month of not having it. Its super light and wont fill a tampon and barley a pad...could this be my period or implantation bleeding??? Idk if i ovulated. But if it is my period why is it sooo light...my dr cant seem to answer this and we're in between drs at the OB right now...so its a different dr everytime..