Back down again

This week, after the success I had at training last week, I was feeling quite hopeful as I prepared to take her to training. I had done a little work with her in the garden, and was pleased with her weavers as she was driving through with good speed and single striding the whole way.
I took her back to Northern Suburbs on Wednesday night feeling slightly cautious- this is a much busier club and people are also less accepting for dogs running off and arriving in other dogs faces! I had her out as soon as the beginners had finished and ran a short sequence with her before the other senior dogs had started. She was pretty good, attentive, taking the tire which she hadn't seen before without any fuss and enthusiastically shooting through the collapsed tunnel that she had seen only once before. I praised her to high heaven, gave her the tuckertime roll I had borrowed from work and put her back into the car so she wouldn't scream and annoy everyone while I worked Terra. When I went back to get her she was quiet in the car, a good sign I thought. I took her back down and choose the outermost sequence. Unfortunately there was a fast dog working in the adjacent sequence and she took off as soon as I let her off lead. It took several minutes to catch her again as she kept shooting through the tunnel as she obsessively circled the other dog who was waiting on top of the dog walk. After finally catching her (and apologising- again), I put her back on the halti and asked for many attention behaviours such as circle work, drops, touches etc. When that fast dog had finished and a slower dog was preparing to run I decided to try her again. Unfortunately she did the same thing, doing the first jump this time and then running off to the other dog. At that point I called it quits, recaught her and put her back in the car. I took her out at the end of the night again and worked her on the contacts on lead, which she did beautifully. Feeling slightly despondent, I finished on that note.
On the friday of that same week I took her back to Perth training, where only Tom and myself were present. I asked Tom if she could work first and he kindly agreed. Leashing his dogs and standing well back I warmed her up and prepared to try some weavers with her. I wasnt happy when, after taking the leash off, she bolted straight over to his dogs, who were doing absolutely nothing. This was even worse than running off after dogs that were doing agility- Tom's dogs were standing still! I grabbed her put her back on the halti and had another try. This time she did her weavers but very badly- whereas at home she was driving and single striding at training she was bouncing and going about half speed. I couldn't get her to improve her performance so I tried her on some jumps instead and to my disappointment she had gone back to 'floating' over the jumps instead of driving, with several run offs to Terra who was tied up and watching quietly.
I finished the training session feeling very disappointed- was last weeks good session just a fluke? And would this dog ever get in the ring?