Need some advice/help

Brooke

Me and my bf have been trying to convince are 2nd child for 3/4 months now and this month my period is late by 4 days well last night I started spotting which my periods are usually on time and super heavy with tons of cramping well idk whts really going ok we’ve taken a couple pregnancy test and they were negative and I have no idea wht is going on, any idea wht cld possibility be going on?