Physical pains, unhappiness, lack of motivation...am I depressed?

I'm usure how to tell if I am depressed or what is wrong with me. It seems as if I am hardly ever in an actual -happy- mood. I smile occasionally, laugh rarely and never feel the need to please my loved ones. This doesn't sound like me at all. I used to love to smile and laugh and make others happy. But here recently...everything just seems so wrong. I'm never hungry, never want to go to work (I work graveyard shift at a 24hr grocery store), always zoned out, very unsociable except with my boyfriend. He seems to be just about the only person I care to talk to. He has noticed whatever my deal is. Currently is in Afghanistan and is stationed in NY. Bummer, but he probably has something to do with my unhappiness here in AR. I am always weak and absent minded, it is very hard for me to pay attention to things, I have recently been getting horrid headaches and hurt all over 24/7 and the medicine doesn't help at all. Honestly I don't ever feel motivated to do anything, not even go cash my checks. I severely dislike sleeping because it makes everyday go by so fast since I sleep during the day, I want to do things but I can't convince myself to take any type of action to make an effort. Every day feels like it's just the same as yesterday, one long continuous day. And I don't like it. I'm only 18, this isn't how my life is supposed to be right now.