Vit D 71nmol/L
I would suggest 4000iu daily. A very good supplement, only two ingredients - Vit D and extra virgin olive oil to aid absorption - and a very reasonable price is Doctor's Best D3. They don't do a 4000iu one so you could take 2 x 2000iu daily
bodykind.com/product/1315-b... - £7.85, delivery £1.95 if order under £15
healthmonthly.co.uk/doctors... - £8.74, free delivery
Or you could buy the 5000iu strength and take one five or six days and week (cheapest option)
When taking D3 there are important cofactors needed - vitamindcouncil.org/about-v...
D3 aids absorption of calcium from food and K2-MK7 directs the calcium to bones and teeth where it is needed and away from arteries and soft tissues where it can be deposited and cause problems.
K2-MK7 good brands - minimum ingredients, extra virgin olive oil to aid absorption
D3 and K2 are fat soluble so should be taken with the fattiest meal of the day, D3 four hours away from thyroid meds.
For Magnesium check the different forms and see which would suit you best naturalnews.com/046401_magn...
Iron - if you can tolerate ferrous fumerate then buy a box of 84 from Amazon and take one tablet twice daily then retest.
If you're troubled by constipation and stomach issues then FF will make it worse so you might want to try iron bisglycinate such as Solgar Gentle Iron but you will need more as the elemental iron content is much less.
Take each tablet with 1000mg Vit C to aid absorption and help prevent constipation, take iron four hours away from thyroid meds and two hours away from any other medication and supplements as it affects their absorption.
Fitting iron supplements around everything else isn't easy. I brought my level up from 35, so very similar to yours, to 91 purely by eating liver once a week as I couldn't tolerate iron supplements. If you want to try that then no more than 200g a week, plus add lots of iron rich foods to your diet apjcn.nhri.org.tw/server/in...
I won't suggest anything for B12 because with your level you need to speak to the experts over at the PA forum as suggested. I think you probably need B12 injections.
When supplementing with B12 in any form, a B Complex is needed to balance all the B vitamins, Thorne Basic B and Metabolics B Complex are good.