Vegan Vitamin D3

I was thinking of getting some as I am back on 100% Huel for a while. But instead of having 4x125g a day, which was too much for me to consume and wasn’t losing any weight, I am on 3x125mg a day now ( 1500 calories ) which I am managing ok and lost 2 stone. According to the Huel powder bag the vitamin D is 15ug per day for the 4x125g a day, so if I have done my maths correctly for 3x125g it’s 11.25ug of vit D or 450 iu. Actual D3 is about 7.5ug and 300iu for 3x125mg of Huel ( I think ). The NHS recommend 10ug ( 400 iu ) a day but different websites ( as usual ) have different recommendations, like 400 iu, 600iu, or 800iu for example or 1000 iu. I did have a blood test in 2017 before I knew about Huel, which said my D level was 73.4 nmol/L. D3 was 70.6 and D2 was 2.8.
Which was apparently adequate is what they said. I think I might have another one done now I have been on Huel for a while and being winter. Then decide if I need a 1000 iu a day tab.