I bought myself a dozen cedar arrows, spined for 45-50lb. I bare shafted an arrow out of my bow which is 35lb @28. I draw about 30" so its probably about 38-40 lbs in my hands. I shortened the arrow 1/2 inch at a time until they are only just long enough for me and they are still showing slightly nock left. Had assumed that these arrows would be if anything a little firm for this bow. Problem is all my bows are heavier draw weights than this one. Where am I going wrong?

The arrows could be a little firm for the bow if you were drawing 28" and cut your arrows to 29".  If you're drawing 30" and cutting your arrows to 31", they may well be too weak for your bow, because of the extra length.  If you're using 125 grain points, try using 100 grain points.  100 grain points would probably be a better match for the light cedar arrows you're probably using in that bow anyway.

Thanks! I guess when they assessed them at 45-50 I figured that would be spine enough.