Moody and unmotivated

Is it just me? I was initially so happy i was pregnant. It has been almost 6 weeks plus now and I hasn't been happy since. The nausea makes me tired and unmotivated at home and at work. I no longer feel like going out and meet my friends. Just wish to be get home from work as quickly as possible. I dread train rides and going to work. I thought I will be excited to read all the baby books, but I end up just refusing to do anything. Just feel moody, lazy, tired, unmotivated. I mean deep down I want to do alot of thing but somehow just feel lazy, tired and overwhelmed. Does anyone feel that way?