Rule of thumb for numbered iron shafts is this: 1/2" difference in length, and 4* difference in loft as you go up and down the set. For rough planning, this equals 10-12 yards difference between clubs for the average golfer.
Wedges, however are often different. The past few years, many wedges come only 1/4" (or sometimes 1/8") different in length between classes of wedges. (Classes = PW, GW, SW, LW, +LW). Thus a Vokey 46* and 48* PWs likely have the same shaft length.
Club designer Ralph Maltby recommends a consistent shaft length difference between your wedges.
Check out his wedge fitting link: http://www.ralphmaltby.com/17
For your irons: 2* upright might deal with how you address the ball. If you stand taller than average, or have arms an inch shorter than "average," this might explain it.