Fertility treatments again

I have one baby in Heaven, one baby here on Earth and I am TTC again. I had to have fertility treatments to get pregnant with my other babies and I am about going to see the fertility specialist again to try for another baby. I thought this would be easier if I already had a living child but it turns out it's not. I always heard about people doing fertility treatments with their first child and then getting pregnant without treatments with their second and I had so much hope that would happen but it hasn't. I don't feel like our family is complete but I'm scared about the emotional roller coaster I'm about to be on and what if it doesn't work again? Help!!