Is it normal that i feel this way?

I just found out I’m pregnant again yesterday. This will be my third child. I have a 4 year old daughter and a 1 year old son. I want to be happy about this, but right now all I can feel is concerned for my kids about how they will feel about another baby coming. My kids are so close and the best of friends. Also, my bf has three other kids from past relationships, 2 boys and a daughter. My

Daughter is also from a past relationship.. his daughter is 11 and she doesn’t come around that much because her mom is so immature. My daughter thinks my bf is her dad, they are very close, he’s been in her life for 2 years she doesn’t know any different, plus her sperm donor is not in the picture. I’m scared to have a girl this time and my daughter for any reason feel less special. I’m just overwhelmed and needing advise.