You said that you have lost a lot of your weight through Alli, are you still taking it?
You are correct, that if you are eating that low of a fat count, that Alli will not be effective for you. It can't take away what you aren't eating.
Can I ask, what your exercise regime is like, and how long you have been doing it? Can I also ask what your average calorie intake is?
The last few pounds are the hardest to lose, and 99% of the time, it requires a stricter food intake, and more intense exercise. It's all calories in vs/ calories expended.