Second child - please no negative comments

I am due to have my second child in less than 6 weeks. My first child is currently 21 months old. We were not planning on getting pregnant right away but we were estatic when we found out as we had a very hard time getting pregnant the first time. While I am overly excited for my new bundle of joy to arrive, I cannot shake this feeling of guilt I have for my first born not being an only child any longer. I don't want my first born to ever feel pushed to the side or second best. I know they will grow up and be good friends but I just can't get over this funk that I cheated him out of being an only child for a short period of time. Is this normal?