Might I ask what reason your doctor gave? To my current knowledge there's no blood LDL too low / blood LDL is not an adequate tool to judge any deficiencies.

I'm a last year med student who eats plant-based himself and my physician was very pleased with my very low cholesterol levels.

Blood cholesterol is not 100% necessary to provide your cells with colesterol as they can produce their own. In fact blood cholesterol medication exploits the fact that cells produce a good chunk of the cholesterol they need themselves. PSCK9-inhibitors prolong the half-life of LDL-receptors in the cell membrane and thereby increase the endocystosis of LDL particles which in change leads to SREBP1-mediated reduction of the cell's own cholesterol production. If virtually all blood cholesterol was taken up you would have very low levels of blood LDL but that would not translate to a deficiency at a celular level.

Here's a NEJM published study where blood LDL was reduced to a median of < 30 mg/dl and in some indiviudals even to < 10mg/dl with a positive outcome, way beyond current targets: https://www.nejm.org/doi/10.1056/NEJMoa1615664

Here is another study by the same author concluding that starting lipid medication at levels as low as 63 mg/dl might have positive outcomes: https://www.ncbi.nlm.nih.gov/m/pubmed/30073316/

On a side note, from what I've read I thought nuts did not lead to a higher cholesterol but if anyone has a study proving me wrong I'd be glad to read it as I haven't spend much time researching the effect of nuts.