Quote Originally Posted by Vela
Dogs generally have their first heat between 6-12 months, some have longer breeding cycles and may not until 12-24 months. A complete cycle is over about 6 months, resulting in two estrous cycles a year so I doubt she has had two heats already by the time she is six months. Some puppies have had heat cycles as young as 4 months, but she still wouldn't have had time to have two even if that were the case. It won't hurt her to spay her and ought to be done as soon as possible.
I don't think the dog is 6 months. I took it as the OP thought the time to get spayed is when the dog is 6 months old but since the dog is older than 6 months, she thought it would hurt the dog...if that made sense...

Like others said, she should be completely fine, and probably better off in the long run anyway, please spay her!