Re: New, Confused... Please help
I would definitely try raising your iron levels. Even if your actual blood iron levels are within range, having such a low ferritin means your body has virtually no reserve. Things like having blood drawn would then lower your iron levels, but your body has nothing to get more iron from, causing a crash.
Cold, fatigue, brain fog, constipation, hair loss... all can be symptoms of anemia. Otherwise as FinnMaid said, you FT4 is on the lower side, so I don't know if this could be the problem.
Still, you have symtpoms of either anemia or hypoT, but have lab tests that say iron deficiency, so that's where I'd look first. You might also try and do a 24h saliva cortisol since you insist that you "can't be held back" which means you could definitely be causing fatigue on your adrenals and pushing through, causing more or stronger symptoms overall.