No, it wasn't enough yeast. You tossed in about 100 billion cells and you would want around 300 billion...there are more reasons than hitting your attenuation to pitch a proper starter too. To ferment out that big a beer you really want to start thinking about yeast days ahead of brew day. Make your starter, use nutrients in your starter, us pure O2 in it and use a stir plate (ideally). Then, hit your wort with more O2 and yeast nutrients and you should be set for a solid fermentation. However, obviously that is in the past for you and you need help with what you can do.
If you mean sunday, as in today sunday (props for brewing a beer already, its 7 am for me in Seattle) then I would run down to the store and pick up another couple smack packs and hit it with the proper pitch along with some yeast nutrient. If you have the money I would also grab an O2 setup and oxygenate the wort.
If you mean a week ago sunday then never mind about the O2. I have no experience with yeast nutrient or energizer helping a week into a fermentation if you are already a week in. However, I doubt it would hurt anything to try. You could also pick up another pack of yeast and smack it and when it gets going strong dump that into beer to give it another shot of good healthy yeast and hope for the best.