i can really understand your concerns.
It seems like you are suffering from female androgenetic alopecia
(FAGA),NORMALLAY we dont do any specific tests to diagnose the problem as the history and physical examination are suggestive.But in females if someone is not sure then they can do routine haematological and full biochemisrty blood tests along with Thyroid
funtion tests and serum iron
,ferritin and vit b just to make sure.
There are treatment options available
Hair spray or lotin which can stop the hair fall
and can make the hair thicker and stronger but you have to apply it for a year contiousely to see the results.
2:Tablet Perfectil,specially formulated vits for hair,nail amd skin.
3:proper balanced diet,good night sleep and lots of fresh vegs and fruits plus milk.
4: some of my colleagues have tried laser hair combing and you should consider this option aswel.
i hope the above mentioned answers will help you.
thanks alot and all the best.