Being pestered to get married but not ready for it

Virginia
My boyfriend and I have been together for five years. Five long...Hard...Tough years. We have been through one deployment, two break ups and hard times. BUT what couple doesn't have a hard time. We are expecting our second child and this whole time family has asked why we aren't married. Yes we have two children but it doesn't mean to hop on the wedding wagon. I explain to them that we aren't ready. It's not a money thing because we just want don't want a big wedding but something sentimental and simple. They don't understand that we aren't mentally or spiritually ready for it. We respect marriage and know it's a much higher level. He never had a dad and my parents divorced and both remarried. So our example of marriage isn't really good. We will eventually is what I say to end the subject. Are there any other couples who understand where I am coming from? I know I love my boyfriend. I am proud of him stepping up to the plate to be a father and a strong veteran. I am blessed to be a stay at home and he brings home the cheddar(his saying not mine lol). He works his ass off to make sure we have what we need. Is there anything wrong with being content with the way we are for now?