Hi and welcome to the Chiari forum.
The size of the herniation is not the issue, not the classification of it being chiari I...goodness that does not make it mild...ugh, u need to have a CINE MRI to check the CSF flow...an obstruction may be ur issue as overcrowding could also play a role.
Next, have u had MRI's to look for a syrinx?...they should look in the cervical spine, thoracic and lumbar plus in doing the lumbar they can also help rule out tethered cord.
Chiari has many related conditions that need to be ruled out and addressed,.
Chiari I does not mean mild...how u r feeling should determine how to classify the condition .....
If u ever have shortness of breath or a drop attack get to the ER right away...
Next, u need a true chiari specialist....u may have to travel to get to one...but it is well worth it.....I am adding a link to a list of drs compiled by the members here, the names r names of the members drs and r added to the list once they feel they were able to treat chiari and they liked them- this is not a referral u should research all drs on the list.
http://www.medhelp.org/health_pages/Neurological%20Disorders/DOCTORS-LIST-FOR-CHIARI-SYRINGOMYELIA/show/1062?cid=186
"selma"