Late!! Trigger Warning Early Birth Stillborn

Also I'm late only by three days but I'm kind of freaking out yes I know periods can be late because of stress but last time I was late I was pregnant. I was four almost five months when I went into early labor just to have a stillborn broke my heart still breaks my heart. Should I take a test? Or should I wait? Or can I take a plan B at this point? I want another baby but after my last experience I'm not ready