not happy or excited to meet my baby. should I be worried?

This is our fifth baby and she was planned. I've never suffered the 'baby blues' or post partum depression in any way at all before. The last few days though I've just been ultra crabby, irritable and like I just don't want to get out of bed. Not because I'm tired, but because I feel just 'blah'. I was thrilled to find out we were pregnant! Super happy to find out she's a healthy baby girl! Up until Thursday I was happy and excited and couldn't wait for her arrival. Then all of a sudden I have this completely opposite feeling. I'm not excited to meet her and I'm not happy I'm pregnant. Im overwhelmed and i just want it to be over. I desperately want to be happy and enjoy my other kids and my husband and to be excited for this little girls arrival, but I'm not. I had an apt three days ago and everything was fine. Then this feeling hit me. What do I do? 
*posted anonymously because I'm embarrassed to feel this way*