This is a shot in the dark here kinda, but I am shooting a slightly heavier arrow than you but at about the same speed. I have a 5 pin set in 10 yard increments and all five of my pins from top to bottom are about an inch and a quarter.... thats all five of them... not 1.25" between each one.

Just walk back in five yard increments and you'll be just fine... if you jsut got the sight and the sights are all crammed together.. just space them out a bit.... maybe the width of a no. 2 pencil or so... should be a decent starting point.