Ok, just for some comic relief...are you having a boy??? I felt exactly the way you described when I was pregnant. I cried all the time! And it was weird things that set me off. Maybe the hormones are different this time because of gender. Who knows, just a thought!
One time, I told my husband I wanted a very specific meal from this one restaurant so we walked about four blocks away to go there. I was getting hungrier and crabbier with each step I took. When we got to the restaurant, they were closed! I collapsed on the front door mat and cried my eyes out! My poor husband was scrambling to figure out how to help, he said he would try to make me the same meal, he said he would sprint home to get the car so I didn't have to walk back, he would have told me anything just to stop my crying! He was so sweet and panicky to see me like that. Of course, seven years later, he got over that and I would be thrilled for that kind of pampering now <img src="i/expressions/face-icon-small-smile.gif" border="0">
Hang in there, it is good you know the difference between depression and your hormones. Like you said, if it gets worse or doesn't go away, you can get help. But, if it is hormones, I hope you can laugh about it some day too!