Advice needed!

Im 18 and my boyfriend is 20. I have a 1 yr old Pitbull. I am ready for a child mentally and physically. I know there are chances of my boyfriend leaving me to do this on my own. I know it's super expensive and time consuming but I honestly haven't met someone who made me feel like he does. I want a son who looks just like him. I know he will be a great dad. His family is wonderful and supportive. My boyfriend may end up leaving me later down the road but it's worth having something precious! Please give me advice on this whole thing! Good or bad.