Helo,
Welcome to healthcare magic.
Severe hair loss over few months is called
telogen effluvium.
It is a hair loss pattern usually triggered by a physical illness ( like
viral fever,
typhoid fever, hepatitis, etc), childbirth, crash dieting,
weight loss,etc which you would have about 3 - 6 months prior to onset of hair fall.
It could also be due to underlying anaemia and thyroid abnormalities.
You need to check your
hemoglobin levels, serum ferritin levels and thyroid status.
Please have a good diet including green leafy vegetables, eggs, dates.
Your shampooing habits seem fine.
You could also take supplements containing biotin which will strengthen your hair.
Hope this helps you.
Take care.