Healthy Body Fat Percentage for Women: A Comprehensive Guide

Question
I'm 32 years old, 5'4", and 105 lbs.  I run about five days a week, maybe 25 miles a week.  My Tanita scale says that I have 10-12% body fat.  I'm fairly confident in its accuracy because several years ago I compared it with a bod pod reading and they were in agreement.  My question is simply - how much is too little body fat for a woman?  I don't look too thin by any stretch, as I am very small framed.  However, I did have hypothalamic amenorrhea before conceiving my now 10 month old son, and I had to stop running and gain weight in order to do so.  I'd like to avoid having to go through that again for #2 - but I'm nursing, so I don't know if I don't have my period because I'm back in the same boat or because of that.  I don't run nearly as much as I did previously and don't lift at all (excluding my little 20-lb portable gym:).  Would appreciate any information and perspective you have.

Answer
Hi Jenna,
Thank you for your question.
Most women should be at least 15% bodyfat.
I am honestly not sure if the reason that you are not having your period is because you are nursing or because of the hypothalamic amenorrhea.
You should try to start lifting because that will help to build up your muscle tone.
Thank you,
Bonnie