Pregnancy #2 unexpected

I'm 11 weeks pregnant with my second child, my first pregnancy it took 3 years with 4 miscarriages in between. I ended up going into labor with my daughter at 35 weeks and she stayed in the NICU for a week but she is strong and healthy 18 month old. She was born September 15, 2015. This baby took no effort at all ( a faulty IUD and boom) is due September 25th, 2017 I'm terrified of having my kids Birthdays this close together, 1.) Because I was an only child I never planned for a second and 2) i use to be a teacher I've seen children fight over the simplest thing. Has anyone else had to deal with something like this please need advice.