Cant stop thinking about it

Hello! My name is Ashley and I'm nineteen almost twenty. I have been trying to conceive for about a year now. I have asked other mom's if they have had problems and they tell me to just not think about getting pregnant. How can I not think about it. I have two step children who are already 7 and 8. And I wouldn't want them so far apart in age so i have been trying harder lately. What is going to take my mind of getting pregnant? I would like a baby of my own so much and it hasn't happened yet and I want to cry. Sorry if I sound babyish or so. This is just a very emotional thing for me.