Irregular periods and ttc

Hannah
Me and my partner haven't been having protected sex for 6 months now we have sex Nearly every day. My periods are sometimes every 2 weeks some times every 3 or 4. How do I track my ovulation:( so hard and what is wrong with me. We are both young physically fit and healthy it's upsetting me feel like giving up. I have not had a period yet after 4 weeks but did pregnancy test and negative need some help