How Does My Period Work How Come I Don't Get My Period During Varsity Swim Season?

How come I don't get my period during varsity swim season? - how does my period work

We practice every day, twice a day for 5 hours in total. They also eat very healthy. However, my periods stopped completely during the bathing season. Is this normal? The college season is 4 months long. I am not now and never had sex, so I know I am not pregnant.