I agree, you should definitely seek a second opinion on this matter. You should also do your own reasearch and educate yourself on your cat's condition. I'm telling you this because sometimes vets do contradict each other and we, because of lack information and knowledge, find ourselves not knowing who to follow. I found myself ignorant of my cat's illness. Consequence? My cat's inflammatory bowel disease became extremely chronic and dangerous. So, I guess this would be my best advise.
Articles found on web pages ending with the words .org, .gov and .edu usually are very reliable. Magazines often give expert advise on any subject. So, when you do take kitty to another vet, make sure that person is highly experienced, is knowledgeable and has dealt with something like what your cat has with great results.
One last thing, stay positive and hope for the best. If that leg does need to be amputated, don't pity the cat. Cats have an amazing ability to adapt to a new way of living. They can bounce back faster than humans. A three legged cat can live a normal life. Just don't let him get out. Making him an indoor kitty will ensure he doesn't get in trouble.
Sure, if you can. It's always a good idea to get a second opinion, especially if you are dealing with something serious.
Do continue her meds and treatment, of course, but go ahead and schedule a visit with another vet at the same time. If you have one in your area, I would recommend taking him/her to a good sized animal hospital. They have a lot of experience dealing with traumas and accidents, have vets on staff who specialize - just generally tend to see a lot.
I'm sorry your little one isn't feeling great, but it sounds like you are taking good care of your kitty. My thoughts are with you both.