Okay, now that you know that autonomic fibers can be "small", and involved in small fiber neuropathies, here's something else to know...
Small fiber neuropathies can improve, as can neurogenic bladders and autonomic neuropathies.
I fear that people on the forum who do not have B12 deficiency, celiac, or CIDP often think that their neuropathy is something with an irreversibly downhill course, and that is just not true.
All peripheral nerves, INCLUDING AUTONOMIC, are capable of healing.
I have a length-related axonal neuropathy. That's generally NOT small fibers, but thicker fibers, though any fiber can be affected at some point. I was diagnosed with neurogenic bladder about 10 years ago. (urge incontinence) I had autonomic testing that showed problems with the vagus nerve to the heart. I have had abnormal sweat testing. I've had bowel studies which show denervation there, too, (but that's AFTER I was found to have a spinal cyst, so that could be unrelated to the neuropathy.)
Anyway, what I want to say is that later bladder studies were normal. My autonomic testing of the vagus nerve improved during the first few years also. I've not repeated everything, so I dont' have studies which prove everything has improved, but according to how I feel--my overall neuropathy has certainly improved since 2000, even though it has not disappeared.
All neuropathy can improve if you can remove from your life whatever it is or was that was harming the nerves, and if you can give the nerves adequate nutrition and oxygen to regrow. The nerves need to be activated, which means using the muscles that are in the area innervated, even if it's a sensory neuropathy. If you don't get sensations from a nerve, you tend to stop using the muscles in that area, and disuse of the muscles causes atrophy and doesn't encourage nerves to sprout, even when they are capable of sprouting. Nerves need to be well oxygenated--so compression of small blood vessels leading to them, or small vessel hardening from atherosclerosis needs to be relieved and helped from worsening. Massage and yoga help relieve pressure on vessels and nerves. Good diet helps prevent atherosclerosis. Exercise sends signals to nerves yelling SPROUT! Supplements provide the core ingredients for new myelin, or bringing energy down long axons.
For neurogenic bladder in particular---Kegels help, and there are physical therapy methods for the perineal muscles which help--magnetic electrostim chairs that are used in urologist's offices, and electronic stimulators that, like rebuilder, can be used at home. I have a device for home use. It's covered by medicare, and when something is covered by medicare it becomes covered by all insurance by default. Unless you are having total urinary retention, there is no reason you'd ever need to self-catheterize. (And, if you are having urinary retention, it would be very important for you to ask yourself a couple of other questions---related to cauda equina syndrome--do you have back pain? Have you had an MRI of your LS spine to look for spinal stenosis?)
I suspect you are having some problems with urge/stress incontinence and not retention. If I'm wrong, please do read up on cauda equina syndrome. If I'm right, you could benefit from physical therapy for the perineum.
So, take heart. Take your supplements, exercise, keep stress down, and things might get better. Autonomic neuropathy is not a death sentence, nor a sentence for inexorable decline. Idiopathic neuropathy disrupts life, but is generally manageable, AND, I am convinced from my experience here---if you have idiopathic neuropathy, you probably had an exposure to a neurotoxin (be it a chemical or antibody or microorganism) at some point in your life, which will probably not be identified, and the task is to move forward living a life as free from neurotoxins as possible.
--- LYME neuropathy diagnosed in 2009; considered "idiopathic" neuropathy 1996 - 2009
---s/p laminectomy and fusion L3/4/5 Feb 2006 for a synovial spinal cyst