[Sweetlips6]

Bonnie just turned 6 mo. (and 5 lbs) the 29th of March. She is scheduled to get spayed on Thursday. But yesterday and today, I have noticed her paying a lot of attention to her private area. I have checked, I did not see any discharge of any kind or swelling. But i am worried that I have waited too late to have her spayed this time.
My question is: Can she be spayed during her heat? If not, why not? and if not, how long do we have to wait? Thanks