You extraction rate or your mini mash was probably pretty low with the high temps you described. I ran the recipe through pro mash and the OG you achieved is pretty much what you would get without much input from the mini mash. What temp was the wort when you took your gravity reading.
You probably ended up with a few fermentables and lot of tannins from the grains. The extreme mash temperature probably killed nearly all the enzymes necessary for proper conversion. I wouldn't worry too much about that as there is a large amount of other fermentables to offset the effect the tannins may have.
You simply have a lighter beer than you intended and a few parts of your brewing process that you can improve upon.
Now, go out and buy yourself an accurate thermometer and start a new batch