If you're going to wear a spur, I prefer a longer one, for exactly the reasons you're encountering. You should not have to distort your leg position to engage the spur. You are wearing the correct length spur when a extra hard squeeze or a *slight* toe out movement engages the spur. Doesn't sound like that's happening in your case.
This is, of course, assuming that your leg is stable and controlled enough to only engage the spur when you want to.
It might be helpful if your posted a photo of you and the horse. The horse's conformation, and where your leg falls on the horse's side, influences your choice of spur as well. So a spur length or shape that works for one rider might not work for another rider on the same horse.