My ferritin was at 18 and I felt major affects from that -- very cold, especially hands and feet, extreme fatigue, foggy brained, etc. Check out your
fingernails. A little lesser known fact is that
vertical raised lines in your fingernails can point to anemia as well as spoon shaped nails. It's called kolynchia if I remember right and I have it. 18 ferritin is low especially for a male.