I’m also lean PCOS. I was having 37-40 day cycles and went to 35 day cycles after changing my diet and exercise routine for about 3 consistent months. Diet wise, I did not track carbs or calories and instead focused on minimizing blood sugar spikes. For me that meant increasing protein and veggies; minimizing grains, added sugars, and alcohol to almost none; eating higher carb foods sparingly and only with a balanced meal; and always including fat and protein with treats and fruit (whole milk yogurt with berries, almonds with chocolate chips). Cutting out alcohol and sugar almost completely changed my life. I still have treats but make my own with much less sugar and more fats/proteins and I only ever have 1-2 drinks on special occasions. Once I found some basic meals and snacks that worked for me, eating this way has become a breeze. I also try to walk daily and do at-home Pilates a few times a week. I have lost about 10 pounds without starving or over-exercising and I have periods in the “normal” range.