My advice....cut your strips smaller (I use 2" strips sometimes even 1.75" strips) or use a larger seam allowance when you are attaching the binding before folding it over!
An easy way to determain how wide to cut your strips is to take a scrap of fabric pin it where your .25 seam allowance would normally go and then fold it over to the back (or front whichever way) and then cover the stitches by about 1/8 inch. then put a little pin in that spot. remove the pins and measure from the edge to where you put the second pin. then DOUBLE that measurment. that is how wide to cut your strips and not have a bunch of space between your stitching and your binding!