I'll be really interested in any other replies. For me, there is a lot a question about the efficacy of the flu shot (for instance which strain you might be exposed to) and that makes the risks seem unacceptable.
I believe a major risk is the possiblity of an allergic reaction. Also many less worrisome, but very uncomfortable, reactions are very common. In addition, I believe that my healthy little lady could withstand the flu were she to get it. I do worry about illness, however, especially since DP is babysitting another toddler who is also coughing in DD's face and giving her big wet kisses. And last year I worked in an ICU with four healthy people fighting for the lives because of the flu. One 40 year old woman didn't make it. Seeing as how I was in such close contact with these people and because of all the reports that children were at extreme risk, I did labor over my decision. I know that the vaccine is usually well tolerated and so selectively vaccinating is something I struggle with at times. Even weighing the available evidence carefully, this is a case where I decided follow my instincts.
In terms of breastfeeding, it certainly is good for the immune system. If your little one does still catch the flu, I don't know that it will "save" you. Maybe is will shorten the duration and decrease the severity due to a healthy immune system, or maybe not.
Last year's H1N1, in particular, based on media reports and my experience caring for flu patients in a small community hospital, seems to have hit some very healthy people the hardest.