You fail to mention whether the beer was fully carbed or not. I'm going to bet that at only 1 week it wasn't.
Until a beer is actually carbed up you really don't know how much body it really has. Co2 adds that feeling of fullness to the beer. Think about soda in a fountain dispenser, like at your favorite fast food joint. You ever pull some that wasn't carbed? It was thin and watery, not because the mix of liquids was off, but because the gas was not saturating the liquid.
Granted your recipe might be thin on body, but I'm betting the issue is more that everything is not fully developed yet.
The
3 weeks at 70 degrees, that we recommend is the
minimum time it takes for average gravity beers to carbonate and condition. Higher grav beers take longer.
Stouts and porters have taken me between 6 and 8 weeks to carb up..
I have a 1.090 Belgian strong that took three months to carb up.
Temp and gravity are the two factors that contribute to the time it takes to carb beer. But if a beer's not ready yet, or seems low carbed, and you added the right amount of sugar to it, then it's not stalled,
it's just not time yet.
Everything you need to know about carbing and conditioning, can be found here
Of Patience and Bottle Conditioning. With emphasis on the word,
"patience."
Give it time and see if it doesn't turn out fine. Don't go by what it is YET. The beer is still going through a process.