Your goal is doable as long as you are willing to put forth the effort.
The first thing you should do is throw the scale in the trash and set your goal to become lower in bodyfat not lower in scale weight. Scale weight is very deceiving.
Losing bodyfat you will become lean, mean and sexy. When I made
my transition my scale weight has NEVER changed.
The second thing I would do is start
weight lifting. Building more muscle will increase your metabolism. I would alternate days between weights and aerobics with one day off per week. Your diet should be the toughtest thing to modify but if you have made it through the first two weeks of the atkins you should be fine for a while.
Welcome to DF and Good Luck!