How Long Does It Take....?

For Iron Supplements to start working. Apparently my Ferratin levels have been low for awile (like I am talking a year) ... and I just started Iron Pills about 3 weeks ago. But my hair is still breaking and shedding like CRAZY. I was told upwards of 2 months and complete repair (cause I have lost a lot of hair to breakage) in about 6 months - If I have been mildly Ferratin defieciant for upwards of a year - HOW LONG does it take. I am only 29 years old, I don't wanna lose my hair anymore. I am so depressed, please help.