Your extremely low body fat level has likely lead to some serious health complications!
I think the lower safe threshold for female athletes is around 13%.
It has definitely affected your hormonal system, since hormones are cholesterol/fat dependent.
Your depression is a natural complication of this low-fat environment and artificially remedying with anti-depressants will only make things worse!
Your tests for the thyroid are flawed and inadequate!
You need a comprehensive stress profile, preferably a saliva test which measures 4x cortisol and DHEA-S.
As a reference only, visit BioHealth labs website for more details.
Your thyroid function could be compromised but your blood thyroid tests would not show this, because you likely have elevated reverse T3 (not tested for), and while circulating blood thyroid hormone levels are fine, you likely have a functional deficiency because of thyroid resistance (it does not enter the cells).
In such cases it is NOT recommended to treat the thyroid as usual.
Treating the adrenals first is imperative! Stressed adrenals would explain the hair loss./thinning and perhaps the acne.
If needed, a minimal dose of T3 only like Cyromel, as a trial might be OK., but you should ask for free T3 and reverse T3 testing, to confirm.
Organ shrinkage occurs in low fat environments as lowered immune and brain function.
Endurance athletes do better with medium to high fat diets , composed of 32%-40% fat, the ideal level for not compromising their immune function.
Endurance exercise puts very high stress on the body by producing high levels of oxidation (free radicals)
Also metabolizing and processing fat-soluble vitamins
A,D,E,K would be compromised.
Your running would NOT be affected, as a matter of fact it would be improved with a higher fat diet!
Don't buy into the low-fat myth any longer.
Just choose high quality fats in your diet, and see a good Functional Medicine Doctor to help you restore your health!
I'm an exercise "Buff", cycling-swimming-cardio-weights,
but also a semi-retired holistic health practitioner and I have managed to achieve a perfect balance for myself (and for many others as well).
Should you have any questions, I'm only a couple keystrokes away.