Does anyone know how long hair would stay in the resting phase after extreme (like 9 mo.) dieting/malnutrition

Various stressors brought on a bit of an eating disorder that lasted about 9/10 months. Now my hair is thinning to the point where it is just starting to become noticeable, which has me extremely depressed and worried (more stress!) My hair is also not growing. It used to grow very quickly and grow long, as a few hairdressers have told me. But my hair, including the hair at my temples, hasn't been growing since my hair cut about a month or two ago. I want to use rogaine to make it grow again (along with proper nutrition!) but am afraid to start because I dont want to shed everything out too fast. I'd prefer to wait until my body is healthy enough for the hair to start growing again normally and then use the rogaine to prevent further hairloss due to heredity. So, does anyone know how long hair would stay at rest (which is recovery mode, i guess) after a very stressful, crash dieting and loss-of-appetite filled nine months?? thanx