Hatha yoga by itself, divorced from the practice of sexual magic or transmutation, is useless.
This is because the original practitioners of Hatha yoga would utilize these exercises to gain physical strength and flexibility so as to have greater control, health, and fitness for practicing alchemy in a marriage.
However, Hatha yoga as practiced today is for the sake of lust: identification with the body and sensuality. This is why Samael Aun Weor taught that Hatha yoga is black magic.
And yet, if you find Hatha yoga helps your body to be flexible, strong and relaxed in order to help your asana in meditation and transmutation, then continue to practice it. Just understand that Hatha yoga by itself does not lead to any liberation or development in the Being.
As for practicing yoga before menstruation, I would recommend giving your body a rest, given the symptoms you experience when mixing Hatha yoga before and during your period.
Remember that menstruation is a time for the feminine body to relax and recuperate itself, cleansing the nadis and sexual organs of impurities and toxins. Therefore, give your body a rest, not more work!
Regarding excellent practices or techniques of Hatha yoga, you may refer to the Resurrected Master known as Swami Sivananda.
For thirty years I sought God. But when I looked carefully I found that in reality God was the seeker and I the sought. -Bayazid al-Bastami