You should give him space to make his decision. You need him to make the right one...
U should marry him first
you'll have to tell your boyfriend how you feel, and why.
If you are not wanting to have a child, don't have one for the sake of holding onto him. Him wanting a child and you not wanting one could be a deal breaker here in this relationship.
he needs to understand and accept you don't want to have a child. period