Don't worry! 15 yards is close for a G-19; and especially if you're practiced with it. On crowded public firing lines I'll often get shut out of the 10 yard targets. So, I just move over to the 25 yard targets and shoot there. Your groups will open up a little; but, in my experience, not enough for a reasonably skilled G-19 shooter to fail to score consistent hits on any humanoid (IDPA) target.
'Wisdom To One Is Foolishness To Another; But, Alas, A Fool Knows Not The Difference; And, The Road To Hell? ...... It Remains Well Trod By Those Who Should Know Better.'