I wish I could comfort you, but my mom went from about ii to i/ii to i after menopause. She lost thickness after pregnancy that she failed to regain as well.
I would focus on eating right. That is the main source of health & good healthy hair. No matter how worried you are, if you don't eat right it is only going to get worse instead of better.
Do this and re-evaluate in 3-6 months' time.
I would also continue to take the vitamins as per what the doctor told you.
Also take a look at little review https://www.wubmed.org/blog/ultrafx10-formula-reviews/ cause it can help and then consult with your doctor.
Good luck.