Leash aggresive

Question
I recently rescued an 11 month old lab and she is very sweet and friendly to people, and occasionally good with other dogs.  When we go on walks she barks, growls and whines when she sees other dogs.  She is in a training class right now and seems to be getting better with the dogs that are in the class, but I want to be able to take her to dog parks and take her off her leash to play, but I am afraid that she will attack other dogs.  I am sure some of her agression comes from sense that I am nervous about her reaction to other dogs.  

Answer
The class is an excellent experience.  I wouldn't ask more of her for now.  Go to the instructor for more guidance on this.  He can see things you can't describe well for me.  If he, she?, is any good, he should be able to sort true aggression from just wanting to play.  He should be able to point out some of the signs so you can learn to recognize it too.  

Most 11 month old Labs love to carry on with other dogs like they were trying to kill one another.  See http://www.photolocker.net/images/Labman/labmanellagretchen.jpg  Gretchen and Ella really enjoyed having her here for a week.  Gretchen was an only dog, and all the ones in Ella's home were older and past such play.  This can be a problem with strange dogs.  Some are more interested in rough play than others.
Gretchen had a great time with my nephew's German Short haired Pointer too, but not my brother's older female Lab.  When you do start taking her around strange dogs, try to keep it one on one and stick to young males at first.  They tend to be more play oriented and more tolerant of females than other females.  

Try to relax too.  You are completely correct about your anxiety transferring to her.  It is very difficult to hide your emotions from your dog.  Just think positive.