I think you mean if my levels are this low, is it impossible for me to “make” vitamin D? You do not absorb Vitamin D from the sun but going out and having the sun “strike” your skin then allows for the Vitamin D to be “made” in your skin and then eventually used throughout your body.
So to improve your “Vitamin D levels” you either need to go out in the sun more when it is highest in the sky and summer time or close to the equator or take supplements. It is not true that you cannot increase your levels from sun exposure when your level is low.
As a side note I hope the 50,000iu that you are taking each week is D3 and NOT D2. The D3 is better for humans!