You could always swap your Wilson Combat Compact or X-Compact whichever you have for a 17 Round Grip with Magwell.
If you purchased your Wilson Grip from Wilson Combat you have 60 days to Return it or Swap it.
* If it was a "Compact 3.9 Slide" the Carry is the 17 Round Full Grip Version.
* If it was a "X-Compact" 3.6 Slide" the Carry II is the 17 Round Full Grip Version
I Purchased a Wilson Carry from Wilson and then another from OCG...don't ask it's a long story.
Then when the Compact Grip's came out at Wilson Combat I returned the Carry and got one.
Turns out that I liked the Full Grip of the Carry much better.
Wilson Swapped my Grips without any questions and no charge
It cost me $8.00 to return my Grip but Wilson sent me the next grip for free.
However if you are sold on your 15 Round Wilson Grip.
Then take your 17 Round Mag to the Range and forget about any gap between the Baseplate and the Grip.
In fact get yourself a couple of 21 round mags for the Range