Holly, I go to another message board and there are several woman on there whose husbands have had vasectomy reversals and they still cannot get pg. It is not something that can easily be undone. There are also woman on this board and on the other one that have had their tubes tied and regretted it. I can guarantee you that you will change your views, thoughts and morals hundreds of times before you are even 30. I think if you just got on the pill (no big deal, take a pill one a day with your vitamins)that would solve the problem. Why do something that cannot be changed when you can do something to prevent pg as simple as one pill a day.
By the way, I think it is fantastic you found a guy great enough to take on a child and treat it as his own as young as he is. You are very lucky...wouldn't you want a child that was part of both of you?