Thaleia - I was miserable for the whole of my first trimester when pregnant with DD - it wasn't just the sickness, but like you I felt overwhelmed and not ready and not sure we were doing the right thing etc. I was very gloomy, doubted my relationship, didn't want to tell anyone because I thought they'd judge me for not being happy, that kind of thing.
Then at some point a switch just turned and I was fine again and I really enjoyed the rest of my pregnancy.
Likewise, this itme, although the nausea is not so bad, I am feeling quite down and almost depressed - snapping at people, struggling to be cheerful about anything, weepy, anxious about moving soon, questioning my relationship again. DP and I are bickering a lot, which is horrible.
I think there must be something about the 1st trimester hormones that acts like a depressant on me. I had fairly severe depression in my early 20s that got a lot better when I came off the pill (Microgynon), so I know I don't react well to some hormones.
I think it's fairly common to feel down and depressed in pregnancy, but I think often, as with me last time, it does suddenly get better. I hope this is the case for you! And although it's horrible to keep feeling like you're hanging on and hanging on, you do just have to believe that things will get better, and just try to be kind to yourself in the meantime. I think that's all we can do.