Changes in Aerobics, but Still Plateau'd

so those are what I see right away.
and here are the questions I have for you:

1) How did you come to your goal? I.E. when you sat down and thought about where you wanted to be, what made you pick 140 (or what ever your goal is)?
2) Why are you under your calories? Is there are specific reason? Or are you just under the impression that the bigger your deficit the more you will lose?
3) What are your goals, I mean your real goals, not weight, weight really shouldn't be a goal, it can be a PART of your goal, but weight in and of itself shouldn't be your goal.
A good goal example is something like "I want to fit into a size <X> dress and be able to do a 5 K in under 25 minutes, and have a body fat % of 18 by the end of 2010 by doing hard cardio 3 days a week for 45 minutes a day, and doing Anaerobic interval training 2 days a week for 30 minutes, and eating a healthy balanced diet with a small deficit.

Remember weight is arbitrary, two people can have the EXACT same measurements, height, age, sex, and one can weigh 25 to 30 lbs more than the other one, weight shouldn't be a goal IMHO.

1. I chose 140 because that was (approximately) the weight I was last time I was the size I wanted to be. [To answer #3 here as well] my true goal is to be a size 8. To that end, I'm probably going to stop in between 145-150lbs, as I'm in some 8s now, but they don't fit the way they should. My other goal was to monitor portions and make better choices in what I eat...there was a point I was eating probably 3000+ calories a day! *shudder*
2. I'm under partially because of your theory above, but partially bc I've changed my eating habits such that I'm eating 4-5 times a day and that's what I'm coming up with. So perhaps I need to restructure what I'm eating again to add more calories.

A few questions I have is how often do you eat? Also, are you reaching your target heart rate at each workout? Since you're working out that much it seems like your body may need more than 1200-1300 calories a day. You may have actually slowed your metabolism down a bit. Also, are you getting enough sleep? Finally, those who have more weight to lose actually lose weight at a higher rate. Once you get closer to your goal, the weight loss will slow down because you have less to lose. That's natural. Make sure you're eating three meals and two snacks a day, drinking lots of water, and are getting enough sleep. Oh, and also that you're reaching your target heart rate as well. You may actually have to put more effort into your training to lose that last bit of weight. Good luck!

I eat every 2-3 hours until dinner, then I *try* to stop eating after that, which is usually around 7pm-ish. I have a HRM, most workouts it's beeping that I'm out of the target range, but I'm not sure how consistent is, or if there's a magic number I'm supposed to be reaching. I get plenty of sleep - usually 6-7hrs/night (I loooove sleep). On the average day, I eat something like this:

breakfast: yellow apple
mid-morning snack: strawberry jello
lunch: subway oven roasted chicken sandwich + lays light chips
mid-afternoon snack: varies between jello, fruit or 5 ritz crackers
dinner: usually - sauteed chicken + green beans or 500 calorie pasta dish, could vary depending on the night

I think based on what SHBoss1673 and you are saying, the probably might come from calorie consumption....do I still need to change my exercise or maybe just push more with the exercises I'm doing?

Good help guys, thanks!