glad you got a little reprieve last night.
as to the supplements - research suggests adults use about 4000 IU per day. many of us here are taking daily doses in line with that recommendation.
yes 125-150 is what you want to aim for after diet/supplements. research has investigated ms risk by dividing a large group of people up, measuring their d3 levels, and seeing who got ms. the group who had the least risk, ie the group with levels 100 nmol/L and higher, had the lowest risk of ms. most doctors will say you're fine if you're above 70 nmol/L but that is about keeping levels of parathyroid hormone in line so that you don't develop osteoporosis. you have to get well up over 100 to see the benefits for the immune system. you don't want to go over 250 nmol/L due to risk of hypercalcemia. that's where the warnings about vit d3 toxicity come into it. anyway there is 30+ years of research looking at vit d3 and the immune system.
vitamin d3 uses magnesium for absorption. i used to take 4000 IU per day liquid vitamin d3, and i took it with a calcium magnesium zinc liquid supplement at the same time. i developed some new symptoms and did not realize until a pharmacist clued me in that i had trouble because of suboptimal magnesium. he said to take some extra magnesium at a different time from the d3, which i did, and my new symptoms resolved. it took a long time for me to build up stores, but now at last i can manage days off from magnesium supplements without my worst deficiency issues coming right back. i had tested in the .8 mmol/L range when i felt bad and i have tested in the .9 mmol/L range when i felt good. so the ranges in the research work for me
a zinc test will tell you whether your levels match those seen in an ms patient, or those seen in a healthy control. zinc is not used by doctors as a diagnostic test. if you tested 13 umol/L serum zinc, the docs would say 'that's normal'. which is true, but ms patients are all clustered in the low end of the normal range and healthy controls are all clustered in the top end of the normal range. zinc affects your liver's ability to absorb vitamin d3, among many, many other things.
i used to be way worse than 13 for zinc, more like 8.6 umol/L. when i got back up into the high teens, my d3 absorption tripled. ie taking the same amount made my levels jump up three times higher than expected. also once my zinc was up close to optimal, my uric acid level shot up for the first time in years.
for uric acid the normal range is 140-360. over 360 there's risk for gout. ms patients average 194 umol/L serum uric acid. less (~160) in relapse, more (~230) in remission. i learned about uric acid before zinc. first i got tested and came back 'normal' at 194. then i learned that 194 was the ms average. then i learned what the levels in healthy controls were (290-300) and started trying to eat gout-inducing foods to get my uric acid levels up. it didn't work. in the meantime i was investigating zinc and figured out i was deficient and worked to correct. then i started testing zinc and uric acid together. when my zinc was 8.6 my uric acid was static, stuck around 188-194 for years. when i supplemented zinc i got up to 16.1 umol/L at last test, and my uric acid had shot up almost 100 units, to 278 umol/L.
so for sure my body systems are functioning better, but i can't say i can feel that difference specifically. one thing that changed that i could feel, was how my brain and eyes were working. i was so messed up at one point that i could barely drive and almost lost my license. i never have those spatial problems any more.
it's my hypothesis (aligns pretty well with a health approach called 'orthomolecular') that making sure you have the right nutrition to ensure that your tests match the status of a healthy control, that you have the best chance of *being* that healthy control. there are other factors to consider but with nutrition, supplements, and testing you can get a pretty good picture of what's going on.
hope that helps and i'm here if you have any more questions