Am I selfish??!!

Don't know if this is considered a controversy but:
So we found out about 3 months ago our beautiful little boy has autism. In now way had that affected the way we love him but it has changed our "plans" for the future. He is very bright and I guess you would say "low" on the spectrum. After finding out our diagnosis we decided to wait on having another child until we thought it would be a better time and after he received early intervention. 
Well this morning after not getting my period I took a left over test and BAM! Clear as day positive pregancy test. Is feeling excited and at the same time fearful selfish? And it is selfish for us having this other baby while trying to make sure our first born has all the attention(for therapy) and it could affective him or maybe not.
I guess maybe hearing from other moms in my situation might help knowing it will be ok and it is do able.