I am an out of wedlock mom.?

The court will not allow the child to be adopted by your fiance. If you were married, the court would only allow the stepfather to adopt the child if the birth father agreed and even then it's not likely to be allowed. The man on the birth certificate is presumed to be the father. The only way you can change that is to challenge the paternity, ask for a DNA test, and see what the results say.