tips for thicker hair.

I have naturally thin hair.  I always feel like I am going balled.  Low self esteem I guess.  I only put my hair up when I either go somewhere or if I go outside with my 6 ur old.  I hate having my hair in my face. I don't put anything in it when I do put it up.  What can I do to thicken my hair. I have biotin shampoo and conditioner.