Hi and welcome to the Chiari forum.
First, the length of the herniation is not as important as how wide it is OR if it is creating a CSF obstruction, this is what causes a syrinx to form.So, the next testing should be a CINE MRI which shows if there is any restriction to the CSF flow. Then MRI's of the complete spine...cervical, thoracic and lumbar should be done to rule out any issues, be they disk, syrinx or tethered cord.
A NS (neurosurgeon ) is only needed IF you have an obstruction to CSF flow, surgery is done to restore flow....so unless or until you have an obstruction surgery won't be an option.
Chiropractors are a NO NO...!!! ANY manual manipulation of the neck is out of the question.
In addition to the cerebral tonsils being herniated and wedged between your brain stem and spinal cord, and if you have a partically retroflexed odontoid this will make the area even more narrow allowing even less CSF to flow....and with any manipulation of the neck they could constrict the area even more, putting compression on the spinal cord or brain stem!!!
All of us have learned our "normal" sensations or feelings we get are not " normal" but actually symptoms, but like you said since we have always felt them, we consider them "normal" until they get out of control and increase in pain levels or frequency.
I hope I answered your questions, if not ask again, or if I created new questions to form, aask here...just know you are not alone.