Is this bad?

So I have a 3 year old son, he's my only child and my husband and I constantly get asked by family members and friends when we are going to have another child. I had my son at 17 and I am about to be 21. I've been in school to get my career going and my husband has his career in the union. We are doing really well and are content with our lives with just our son. We always tell people no we won't be having another child and people get like on our case like omg why? With a tone like it's something so bad to not want another child. A few of our friends that ask us about another child tell us how hard it is with 2 kids and they have kids really close in age and we see how much they struggle when we get together. We are content and happy with just our son is it really that bad to not want another child? They make it sound like I'm such a bad person to not want another child.