Do we really want to say that our government has the authority to force its citizens to procreate? This is borderline ridiculous. REPRODUCTIVE RIGHTS. It is not a moral wrong for someone to decide that they don't wish to procreate. It is their life, their genes. Let them do as they please and propagate (or not) as they themselves see fit.
Perhaps you don't want children because you do not feel you can care for them and grant them great opportunities. Perhaps you do not want children because you feel their quality of life or yours may be endangered for genetic reasons. Perhaps you do not want children because you do not want the responsibility of caring for another person. Perhaps you do not want children because your religion, philosophy, or personal beliefs ban sex, marriage, worldly partnership, etc. which prevents you from copulating.
All are selfish. None are wrong.
Some people cannot afford a child, some people are unable to have a child, and some people simply do not want children. Children are one of the biggest responsibilities one could ever have, and the parents must be willing to make the sacrifice. Just because someone does not want children does not mean they are selfish.
In fact it is often quite the opposite. For example if you do not want a child due to financial reasons, personal reasons (such as not feeling very maternal, have a condition holding you back from looking after a child, alcoholic tendencies etc) or other reasons, you are actually being the opposite of selfish. What's the point of raising a child if you aren't prepared to look after that child properly? It is best to be the best parent you can be or to simply not be one.
Ask yourself this: It is more selfish to have children for the wrong reasons or to not have any children at all? One of the answers that some people give when they are asked about their motive to being a parent, they say, "So I'll have someone to take care of me when I'm old". Isn't that selfish?