What is the legal effect on the father of an illegitimate child who subsequently marries the child’s mother?

Someone told me that because my wife and I got married 2 ½ months after my son was born, that I do not have the same rights as a father that was married at the time of birth, is this true?

You have been incorrectly advised.  Your marriage had two effects:

1.      it made your child legitimate with effect from the date of marriage and

2.      it gave you all the rights and obligations that you would have enjoyed had you been married before your child was born.