hello and welcome tina. im so sorry for your loss but you will find the girls here a great support.
day 1 is normally the first day of bleeding more than spotting (if charting then spotting wouldnt start a new cycle where light bleeding would)
miscarriage CAN change things though. it doesnt always, i was lucky enough to have normal cycles after my losses but i know plenty who didnt.
personally i didnt use opks at all my first cycle after loss, i just charted so that i knew what was going on and dtd when we felt like it rather than actually ttc.
i hope you get some answers soon hun. i know how devestating it is but please, feel free to ask anything you need or just rant/cry whatever, we have all been there and know sometimes all you need is for someone to understand what you are feeling.
xx