Just wanted to say hello!
I've only joined up last nite meself.
As for your questions, it would be helpful if you could keep a diary of what you eat and drink and post it in the relevant section, just so that people can have a look and base their advice and suggestions on that. For starters, do you drink enough? Sodas and drinks with caffeine in them don't really count! And depending on what those 12-1500 calories consist of, your body might have decided that it needs more energy than it's getting, so might be holding on to the 'reserves' it's got. It seems that eating little and often, and drinking a lot of water, does the trick.
I used to know a girl who came into the gym every day to work out and lose weight, and became totally disheartened when she didn't. Turned out that she almost starved herself - and drank black tea to get her fluids in! - so her body was refusing to give up what it had!
How often and how long for do you do aerobics? Do you really work up a sweat every time? You might want to invest in a heart rate monitor, to check your heart rate. If it's not consistently raised for about 20 minutes at a time, it won't do much for your weight loss.
Have you tried weightlifting? Contrary to what many people believe, weightlifting is great for losing weight! The exercise makes your heartrate go up, and body muscle requires more energy (calories) than bodyfat, so you'll burn off more of that, even when you don't work out!
If you're new to weightlifting tho, I'd really recommend joining a gym for at least a while, and get an instructor to teach you how to lift correctly. Many people injure themselves, because they go out and buy themselves some heavy weights, set it up in the garage and start lifting, with only the manual as a guide. Don't do it!
Anyway, that's my idea of things, it seems that there are loads of very knowledgeable peeps on this board so I'm sure you'll be getting tons of really good advice!b