I have a short draw (26 1/2")as well..
EVERY Cedar arrow I have ever shot that flew correctly needed to be spined 5-10 LESS than the bow weight... On a non ceter shot bow (selfbow) for example because of the paradox depending on the bow even I have needed even lighter spined POC shafts to get perfect arrow flight. Spend the money and time to get things perfect...!
Your shaft is for sure showing weak.. Accept nothing less than a "ball" of feathers spinning perfectly straight all the way to the target. Matter of fact, years ago I started to only tune arrows shooting broadheads.. They get the job done so tune with them first. Any field tip will be right down the middle after you get broadheads to fly perfectly. Every archer/bow is different. Brace height, release, draw length, nock fit, installed correctly, ect. ect. The arrow will not lie to you. Nock left for a RH shooter is weak... Buy a test "kit" of a few differnt spined shafts, cut to length fletch them and test shooting broadheads.. One spine will be "right" for you and the bow.
If you need quality hand spined/sorted POC's I have bought superb quality shafts from Mike at the Nocking Point... Great prices and even better service with Mike.
In bowhunting,
John III