TTC #1 Help

Hello, Im new to glow. Been tracking some things on glow since March when I stopped taking birth control. My period on BC was normal and every 28 days. Now that I have stopped taking it my first cycle was 31 days and now this month it's been 35 days and I still haven't started. My fertile days keep changing on the calendar for last month every time I update that I haven't started my period yet. We were intimate on my fertile days, but now that the days keep changing I'm not sure. Is it normal for my cycle days to be so off after birth control. I took a pregnancy test Tuesday and it was negative. Should I test again? Thanks in advance for the help and advice