women runners advice : marathon scheduled in luteal phrase

Hello, I’ve been training for a marathon and trainings been going well. The marathons in 4 weeks and have just realised it’s scheduled during my luteal phase 3-2 days before my period. I’m sensitive to hormones and this is always the days leading up is always the worst time running for me (legs feel heavy, more tired, slower paces feel more hard work, heart rate increases). I’ve been looking at period delay pills but never tried these before and don’t really want to do nothing new on race day.. please can anyone advise.