1. Personally I feel that the fortaz was/is probably not nessicary, however you should always finish out the injections once started. If for anyreason something is brewing and you do not finish out the course of anitbiotics you can help to develop resistant strains of bacteria. Fortaz is pretty safe so I would not worry about it hurting your snake.
2. Tube feeding in my experience is not as stressful as even assist feeding if done properly. I actually prefer to tube feed than force feed. The tube is a small diameter and fexible it will not hurt your snake. In the case of your animal tube feeding may jump start her metabolism and she may get hungry. Every snake I have tube fed has turn around and began eating on their own.
3. The only other thing I would have done or asked about was adding flagyl to the food mixture and possibly fenbendazole. If she was mine I would continue the injections and offer an irresistable live asf or gerbil in 10 days or so.