With GERD I expect that you were taking PPI's and other heart burn meds. Hopefully not cimetidine/Tagamet. These meds can led to multiple mineral deficiencies as well as low B-12.
Are you now free of heartburn meds? Might explain low mag.
Any leg or foot cramps or able to contract a muscle and make it lock up? That is a magnesium deficiency.
When did you start magnesium?
We have a lot of guys at your age and hormone condition find their way here. It may not be a common problem, but is with the guys who self-select to be here.
What exactly had Defy prescribed and how are you dosing. Please do not report volumes, but mg's, IU's etc.
Did Defy discuss preserving your testes and fertility?
Gluten/dairy: Why exactly? Digestive issues?
Ferritin 112 is sufficient for thyroid T4-->T3 conversion.
Get 25mg DHEA, take with higher fat and lower fiber meals.
Take fish oil, natural source Vit-E and 5000iu Vit-D3 the same way.
Find a high potency B-complex multi-vit with trace elements including 150mcg iodine and 200mcg selenium.
Vitamin C, 1000 or 2000mg per day, at night may improve sleep.
Sleep: Find 5-6mg time release melatonin, must be time release. Magnesium can help too.
Inject T twice a week for smoother levels. -doing that.
Do labs always halfway between injections, time of office visits can be wrong.
Inject subq with #29 1/2" 0.5ml insulin syringes.
Ignore serum iron, levels change a lot with recent foods.
Your lab screen shots are very difficult to read. Did not see glucose.
Yes, SHBG is low, some are that way, some have causes.
Did you loose blood with your condition and surgery. Labs suggest that you could use more iron and that is unusual for males. GI blood loss is then a concern and an occult blood test is conclusive.
fT3 is oddly high, midrange or slightly higher is good, more may be some kind of compensation. But a good thing overall VS alternatives.