Riedell makes wide widths. So, you may have measured to one of the "wide widths" on Riedell. They fit differently than Jacksons, not necessarily "narrower" - they are different in the heel, the toe box is different, etc etc etc. Plus, there is that split width thing happening. Now, an AA Riedell may be narrower than a AA Jackson ... but, that may mean that you just order a A in the Riedell vs a AA in the Jackson. A guy skater with nice E width feet who I know has Riedells - as do a few females with what would be considered wide feet - but, they have Riedell "feet" and so they fit Riedell skates. We also found the toe box on the Riedells to be higher due to the open throat design they now have on all of their skates ...
Riedells should fit tight when you get them. If you get them and they feel "comfy" they are too large. They have an interior lining that fits to your feet over about 2 or so weeks of skating; at that point, they will be comfortable. If they are "comfy" at initial fitting, they will be too loose after they have molded to your foot on the inside.
Riedell has their own custom skate fitting device. It works well.
It's like street shoes, depending on the manufacturer, I wear anything from a size 6 to a size 7-1/2, and sometimes a AAA and sometimes a B ... I just happen to know what brands fit my feet ...
I am baffled by the Matrix blade though, those are expensive; we debated getting them because of the benefits of being able to get "extra" blades for swapping out to save trips to the skate sharpener ... but, decided it wasn't worth the extra cost. Our skate guy basically proposes them only when someone is a) done foot growing and b) is planning on staying in the same blade for a long time, because you only have to replace the runner when the edge is gone in a couple of years ... did they explain why the Matrix version?