13 Gallons of water and only 7 and 1/2 gallons of wort

So I brewed an irish red with some mixed results. The gravity was on target but I just could not get enough wort. I batch sparge and my first sparge i put 6 gallons of water in and only got 3 gallons of wort. The second time I put 7 gallons of water in and got 4 gallons out! I dont understand??? The wort does seem thicker than normal but my gravity was on target? When i took the grain out the bottom of my mashton it was mostly dry? Its not like I have a pool of water in the mashton. Any help would be greatly appreciated!

Recipe:

60 minute sparge at 154* and 10 minute sparge at 170*


All Malt is x2

6 pounds light LME
.75 lb. Carared
.36lbs Special B
.12 lbs Roasted Barley
.5 Corn Sugar
7.5 lbs Brewers malt

Irish Moss
.5oz Northern Brewer
1oz Kent Goldings

You have approximately 17 pounds of grain there. I would expect you to lose approximately 2 gallons to grain absorbtion. The other gallon you could be losing to mash tun design... Seems a little high, but not necessarily out of the realm of possibilities. Now you shouldn't lose anything during the sparge because the grain would be fully hydrated. EDIT: Also, I'm making assumptions here because you appear to be confusing the terms "mash" and "sparge." I.e., you state: "60 min sparge at 154..."