Beaver, what type of bow is it, i.e. recurve, longbow, fiberglass backed or self, R/D or narrow straight-limbed? What type and relative diameter of string? All of those things can affect the spine you need. Unless you're shooting a self bow, you're probably under. Not everyone fits the average, but this has been my experience.
When you go up in spine, you will also probably go up in shaft weight at the same time. When you get the right spine going for field points, you might have to go up another 5# for heavy broadheads.