is it normal to feel this way?

I'm 10 weeks pregnant. One day I know fiancé and I can do this and I'm so happy and so excited and we can make it and handle it. The next day I'm I don't know if I can do it. I don't know if that's normal and then when I'm down I'm really down :( maybe it's the fact we haven't really told our families but I'm not ready yet. I'm tired of feeling this way when I'm down though. Anyone else feel this way? Any advice?