Feeling guilty as a parent to my first child

Britney
I'm scheduled for November 23rd....that's 2 1/2 weeks! But the last two days I've felt HORRIBLE that I'm having another baby. I have a 4yo daughter who is from a previous relationship and it's always been just her and I (of course until I married my husband, who she calls her Daddy). The three of us have done so well together and I'm so so so so terrified that it's going to be a disaster. Our daughter is truly wondeful-independent, listens for the most part, smart, humerus and above all, an incredibly kind child who can get along with anyone. Should I have wanted more??? Why the hell am I feeling like this all of a sudden. She begged for a baby brother or sister last Christmas, and even though we had finally stopped trying and it happened, we were elated.im still excited and I love our little boy on the way and being pregnant. Every movement makes me so happy still. So What is my problem!?!? I am so ridiculous. Anyone else feeling like this?