It's quite common to go through phases like this when you are pregnant, all I can suggest is to take it day by day and when the baby finally arrives your maternal instincts will kick in and you will fall in love with the new little life you have created.
Don't worry, your baby will be totally unaware that you are unenthusiastic at this stage! All that matters at the moment is that you get enough nutrition and sleep, and worry about the baby care AFTER the labour!

Do make sure that you are taking proper nutritional supplements, particularly iron, as if you aren't it can make moodswings and coping with the pregnancy a LOT harder. Iron deficiency can send you right into a low, much like depression, so if you are finding the pregnancy difficult to cope with mentally it might be a sign that you need to take better care of yourself physically. Otherwise, just write it off as a bad day/week and trust that you'll feel more excited once the delivery date is closer.

Kerrie