Initially calm your reactions to other dogs - she is feeling threatened by their presence near you, so you need to act in a way that assures her the other dog is no threat.
If she does growl at a dog who approaches you, walk away from BOTH dogs... so she doesn't gain your attention by the guarding, but you don't continue to put her in a position where she feels threatened.
Praise all positive interactions with other dogs (be it playing, sniffing or plain ignoring).
If possible, find stooge dogs - one is enough, but more would be helpful. Have both/all dogs on lead with owner. Have a spare person.
Get the spare person to hold your dog's lead, you go and greet another dog, return and reward your dog. (You will need to make sure you do this at a distance/intensity that doesn't elicit a growl from your dog). Repeat with other dogs. Get other owners to do the same.
Gradually increase the intensity of your interaction with other dogs... so build up from just standing next to another dog (if that's all she can cope with), through a greeting, a quick fuss, a longer fuss, giving a treat, right up to playing with a toy.
Make sure you are mega-praising your dog, and don't attempt to acheive all of this in one session!!!
Also bear in mind that the 6 month old Cocker may well just have been at the age where a male dog needs telling off... (puppy license expired, but not yet learned manners). Check the body language and approach of the dogs she is growling at and see whether they are rude in their approach to her or you...
