Kinda hard to look at if we can't see the recipe and hop addition schedule. Export the recipe as a .bsmx file and post it for specific recommendations.
First thing I would check is the %AA for each of the hops to see how the hops you used compare with those of the recipe.
Next, if your 0 minute addition is giving you 3 IBU, I would suspect that you have some whirlpool additions. If this is the case, then I would recommend changing the 0 minute addition to an immediate whirlpool/steep add.
When you do that, you may also want to look at your equipment profile and look at the section where the whirlpool/steep hop addition parameters are listed. There is a box for 'estimate boil hop util in whirlpool'. This will add to the standard IBU for your boil hops, projecting additional isomerization for those additions. If the original recipe did not count any bitterness for whirlpool additions, but contained such additions, then this factor as well as the additional IBU from the whirlpool may account for your increased value above what the recipe stated.