I think my girlfriend would make a good mom
Do you two want to have children together?
I have thought about it, but am afraid to ruin my life with a baby.
Children are a blessing so it is not good to think a child would upset your life. This is really important to know if your girlfriend does want children.
Is it wrong for me to think about having kids and how they will change my life?
Of course, a child will change your life, but you don't have to think about it as ruining it, but rather you would be gaining so much love.