Baby #2 on the way....not sure how I feel.

Finding out I was pregnant for the first time was the most exciting thing ever! I had my first born son Nov 23 last year and he'll be 5 months the 23rd. I just found out we're expecting baby #2 yesterday and I was not excited at all. I feel embarrassed and down about it being that it's way sooner than I had expected while dad is pretty happy about it. I feel like I'm going to rob my son of his time with me because of the new baby. My cycles have been very sporadic so I don't know a possible due date until I see my obgyn. I'm just very unprepared and need LOTS of encouragement through this process. Thanks.