AngelaHi Jennifer,
I am sure that your sister does not think you are crazy! Your confusion is understandable... Most likely she wants you to benefit from her own experience and hopefully save you alot of anxiety and perhaps disapointment by sharing with you what worked for her. Of course everyone is different and as long as you are happy with your doctor’s advice, that is what is important.
You know... if your sister has been there, perhaps you should consider yourself very lucky and be relieved that you know someone with your condition CAN have a healthy little girl. Perhaps your sister feels that her experience as a ginea pig having gone there first is an advantage that you could draw upon.
Either way, I am certain that your sister wants you to know that she is there for you and all she wants is for you to have a safe pregnancy and a healthy baby cousin for her daughter to share life with....