so, how quickly does the acne show up after shaving? are you sure it’s not irritation from shaving itself?

some general advice for sensitive skin:

• use facial cleansers as part of the pre-shave routine (and maybe also after if it is indeed acne. this will remove whatever product is causing the clogged pores as well as the bacteria)
• use a non-gel shaving cream. (or any goop-in-a-can.) instead use something you have to whip up. (I’m not sure what you mean by ‘oat based’ there’s both the goop-in-a-can versions, and poraso has a cream-in-a-tube of the stuff.) (in extreme cases you would want something unscented as well.)
• use cold water, both for the rinse and whipping the cream.
• use a hot towel to open up your skin’s pores. -use a fresh, clean and sharp razor every time. I would also suggest if you haven’t already, getting a sample back of many different brands of blades.
• rinse with cold water, and apply an alum block (and rinse again,) (the styptic pencils aren’t very good. you want a smooth block of alum.) also, in this vein, check your safety razor. when seating a new blade, there should not be any real play with the cap off. the blade should pull into a seat so that it’s constantly centered (and parallel!) on both sides the blade. I found the often-recommended “entry level” Merkur 34c to be horrible in this regard. I now use a Muhle closed comb (if you look at the prongs the blade registers against, they’re more conical to the merkur’s straight pillars, as you tighten it just centers the blade perfectly.)
• use a product with witch hazel in it, I use a post shave balm by thayers which is lightweight and moisturizing as well. this soothes further irritation and mends the dehydration from everything else. pretty much any lightweight post-shave balm will do. Again, look for something unscented.
• use an alcohol based aftershave. among other things, it’ll absolutely destroy the bacteria involved in causing acne. something like eucalyptus green if you want to limit scents (it fades quickly,) but anything traditional aftershave splash will do.