in a  nutshell, yeah, it's bad.  sooner than you think, your system is going to be totally out of whack.  the good news is you make very healthy choices, just not enough of them. i found myself having to chug protein shakes at 10 every night just to get to 1000!  it helps to divide how many calories you should alott for each meal (i.e. 300 calorie breakfast, lunch, 150 calories snacks, 400 calorie dinner)) so you remember to eat them throughout the day, not be stuck in the evening with feeling like overdoing it. 

Well, right now I'm forcing down the rest of my veggies, even though I'm not hungry.

I never thought this would be tricky.

And I'm pretty sure the only days I hit my calorie mark are the days I give in and get a chicken burrito from Pancheros!

I've been thinking about buying a mini fridge for my office so I can stock up there and not feel like I'm bringing in 2 bags of groceries every morning to work!

"What would be the sense in somehow pushing the calorie intake to that higher number?"

The sense is that the higher number is the minimum requirement to keep your body running in a healthy way. It's harder to sustain that kind of eating long term if you have much to lose. As a matter of fact, it would be unhealthy for you. You'll probably run short on energy and you may very well stall out on weight loss.

You know you CAN consume more cals than that...otherwise you wouldn't have anything to lose! [although looking at your stats, you don't have much!] I have days that are a little too light by accident but I try and make sure that I average at least my BMR. Try looking at it from a "I want to get this much (protein/carbs/fiber/fat) a day" angle. You'll find the cals when you find the grams. I just read a study where people who consumed more protein and the same amount of calories as another group, lost the same amt of wt but lost less muscle. That's a good reason to be SURE to get enough protein.

You probably already know that most likely 3 to 4 of the pounds that you've lost are water weight, right? Not trying to burst your bubble, but don't want you to be totally bummed if you consume a bunch of sodium and it comes back.

hawkeyegal and patama, yes this is bad and for your own health you need to up your calories and reach your calorie target (or at least 1200 calories) on 99% of the time.
If you are having difficulties, instead on relying on veggies as your snacks etc beef up your foods. Have a heartier breakfast with some whole grain breads or cereals. Throw a few almonds in there too. For your lunch sandwich put a nice slice of avocado on it or a lovely piece of cheese. For a snack eat 25 almonds which is about 170-200 calories. Instead of 50-100 cal snacks eat 200 cal snacks. You need to eat more and this is why:

Women need to make sure not to eat less than 1200 calories a day MINIMUM. Teenagers (females) need to add 300 cals to that for a minimum of 1500 calories. Men can add another 300 ontop of that. Undereating for a long time can have absolutely deleterious effects on your health.

From Mary Hartley, Calorie Count's Director of Nutrition:

"By eating {so few} calories, you will not get enough energy, protein, fiber, vitamins, minerals and other components of food. In time, you could become malnourished, which can cause severe health risks such as respiratory infections, kidney failure, blindness, heart attack and even death."

Here is a brief reason why never less than 1200 from the Advice section of Calorie Count Plus, under the Q&A tab:

Why must I eat at least 1,200 calories a day when I want to eat less?

In order to get the daily food servings you need for a balanced diet, it takes about 1200 calories a day. With careful planning, you could have a balanced diet on 1000 calories, but the restrictiveness of a very low calorie level can lead to binging and weight cycling, which will take you further from your weight loss goal. What's more, very low calorie diets can cause excessive muscle breakdown and metabolic adaptations, which can drive down your calorie requirements. In the end, you'll need fewer calories to maintain a higher weight

Your body needs at least 1200 calories per day to survive.

Here is a very rough scientific break down provided by a dietician for a 5' 2", 19 year old female weighing approximately 100 pounds, sitting around all day and doing nothing:

-The heart needs 12% of the calories (144 cals)
-The kidney needs 12% of the calories (144 cals)
-The Liver needs 23% of the calories (276 cals)
-The brain needs 23% of the calories (276 cals)
-The skeletal muscle needs 30% of the calories (360 cals)

Are you going to try to eat more for your own health and long-term weight management?

I appreciate all the advice. My biggest goal is not to lose weight, but body fat and to build muscle. I'm already a small-framed, size 2, but I'm not as lean as I'd like to be.

And well, at least I recognize I'm not eating enough--it just felt like a ton when I was packing my lunch, so I was a little discouraged to plug it all into calorie counter and see such a low number.

When you are trying to build muscle, you need to increase your protien intake.  That will increase your calorie intake as well.  Eat low fat protiens such as beans, egg whites, low fat cheeses.  Nuts will give you the protien and add the healthy fats.  Don't ever cut fats too much!  Fat serves as an energy boost, and the body needs it.  Just make sure you are consuming good fats, and in moderation.  Adding a good quality protien drink supplement to your daily routine would not hurt you. 

Keep in mind that too lean is not healthy.  Even professional body builders keep some fat on their bodies during their daily routine.  They do not bulk up and work on getting that cut look until they prepare for competition.  They go on a very strict diet for about 2 to 4 weeks prior to competition, they achieve that cut look just long enough to compete, and then resume a more average diet as soon as competitions are over. 

It amazes me!  I have never had a problem with eating too few calories.  I have to keep track of everything I eat, I can push my intake over 2500 very easily.  Just goes to show how different each person's body really is.  I am always hungry, and I don't fill up easily when I do sit down to eat.