Post apocalyptic society would probably bring about no periods due to starvation in many women.
The jacket could have been her fathers when he was a teenager or child.
And most important of all in a long term survival situation is to ensure you can keep some form of normality and comfort. A morning routine is great for this.
This is because your body weight can get too low to sustain a pregnancy. So to protect the body, the reproductive system “shuts down” because it's severely malnourished.
Any changes in normal hormone levels can lead to menstrual dysfunction, especially in athletes. This can be caused by overtraining, stress, dieting and weight loss. Typically, menstrual dysfunction occurs when the amount of energy used by athletes exceeds the amount of energy taken in through nutrition
Women from postapo movies don't usually look or act no-period starved. Morning routine is nice, but you certainly wouldn't keep up with everything pre-apo even if you had the resources and time. You can make up apologies for almost anything in movies. That doesn't make these things look less ridiculous in general.