Forgot Flaked Oats :-\

I brewed this Russian Imperial Stout yesterday morning,

17 lbs Pale Malt (2 Row) US (2.0 SRM) Grain 1 81.0 %
1 lbs Chocolate Malt (350.0 SRM) Grain 2 4.8 %
1 lbs Roasted Barley (300.0 SRM) Grain 4 4.8 %
1 lbs Oats, Flaked (1.0 SRM) Grain 3 4.8 %
8.0 oz Black (Patent) Malt (500.0 SRM) Grain 5 2.4 %
8.0 oz Caramel/Crystal Malt -120L (120.0 SRM) Grain 6 2.4 %
2.00 oz Galena [12.50 %] - Boil 90.0 min Hop 7 64.4 IBUs
1.00 oz Northern Brewer [8.50 %] - Boil 30.0 min Hop 8 15.7 IBUs
1.00 oz Northern Brewer [8.50 %] - Boil 5.0 min Hop 10 4.1 IBUs
1.0 pkg Irish Ale (Wyeast Labs #1084) [124.21 ml Yeast 12 -
1.00 oz Centennial [10.00 %] - Boil 15.0 min Hop 9 11.9 IBUs
1.00 oz Centennial [10.00 %] - Boil 1.0 min Hop 11 1.0 IBUs

I was about 45 minutes into the mash, when I realized that I had forgotten to put the flaked oats in. So I opened it up and stirred in the oats. I was a little pissed about it at the time, but I remembered, "RDWHAHB". But I also missed my OG by 16 points. Should have been 1.106 and came up at 1.090. Also, not really that big of a problem (except my pride being hurt). This was my first RIS, I just wanted to know if the 15minutes of mash, plus 30-35 minutes it took to sparge, would be enough to get at least some of the head retention and body out of the oats? Any feedback would be greatly appreciated! Thanks

The addition of the oats might have brought your mash temp down a bit, but I'm sure you'll get the mouthfeel/head retention benefits of the oats. The low OG was probably due to loss of efficiency that comes from a big grain bill. Cheers!