Sorry to hear you're feeling like this. I'd also recommend Magnesium and use "Better You Magnesium Sleep" spray. It's lavender scented so helps relax for bed too. It's ironic that often total exhaustion leaves you unable to actually nod off.
Try and get a higher strength Vit D from a pharmacy, or again, "Better You" do a Vit D spray. They also do Vit B12 spray which I think has made a big difference to me (I have an underactive thyroid, fibromyalgia and chronic fatigue, so am always fucking knackered lacking energy ).
When you take your iron supplement avoid tea for thirty minutes each side as tannin affects the absorption. As mentioned, taking it with orange juice increases absorption.
And try to pace your activity. It's hard to do, as when you have energy you really want to make the most of it and get loads done. I try and set a timer on my phone so if I'm doing chores/gardening/de-cluttering I only do it for 20 minutes and then have a rest - not really a sit down, just a change of scene, more to stop me losing track of time as otherwise I'd go at it all for ages and over exert.
Again, like PPs I've found that a low carb, low gluten and low sugar diet REALLY help and I've increased my protein intake by having more eggs at breakfast.
For years I always tried to have forty winks at about 4pm too. Even when my now adult children were younger we'd have "quiet time" when they got home from school. Literally a forty minute lie down with my eyes shut. This gave me enough of a boost to last the evening. Sometimes I'd nod off, most times just being able to close my eyes was brilliant.
It's so different to just being 'tired', when an early night sets you right, so I really sympathise and hope some of the suggestions we've made help you. See if you can get your thyroid levels tested, we are notorious in the UK for having a lot of 'borderline' results with a much wider range of acceptable levels than in other countries (so overseas we'd definitely be diagnosed with an underactive one and get treatment, here it's 'borderline' and not treated). You'll probably have to nag the GP. They don't like testing as if it's under (or over) you need medication for life and as a result qualify for free prescriptions for everything.
Wishing you all the best and I hope you find some relief. Also hope your family understand that you're not 'just a bit tired' but absolutely exhausted, as that makes a huge difference