Fast fashion & menstruation...

The only sustainabile approach on both of these is simple. Refuse, Reduce & Reuse...as always.

If not the above three...Avoid buying anything new (we have to try and focus on not creating more stuff, while the experts figure out what could be the most environment friendly way of dealing with all the wasted stuff which has already been created).
Idea is to become really mindful and aware of what we are responsible for..what business we are supporting...what products we are getting produced more of...are the ventures we support sustainabile?

Eco friendly period...reusable natural fabric pads, panty liners, menstrual cups.

Eco friendly wardrobes...curating the pieces that actually bring you joy, which you like...reducing the amount of 'space' we take that way as well. Donating whatever doesn't go with the above lifestyle.
Trying to borrow whatever we don't have, for occasional use.
Buying/using second hand wherever possible.
And goes without saying... not Falk mg for the 'retail therapy' traps anymore.
Fast fashion...as it is called..is never long-lasting. The products wear easily. Are just increasing the load on our environment.
We buy things in fashion. Waste our precious resources on them, only to see them go out of style within months. Just really wasteful.

Also...Living frugally is also good for the environment. Remember that.
Anything and everything produced and even recycled or donated needs resources...raw materials, fuel for transport, water, power (thanks to all the places where people have being battling life-threatening conditions due to the coal mines) etc etc. So, before buying anything at all..we must think ten times, if we really 'need' or actually just 'want' that thing.

I have said all the above points multiple times in multiple groups/pages/comments/posts too, if you search similar topics.
Good luck :)