I had breast cancer in 2010 and recently 3 brain tumors. Did the necessary treatments (surgery, gamma knife. I would like to know if I am considered disabled because of the remaining life span?

Probably not. Disability is not usually judged by a person's life expectancy, but rather upon loss of particular functions, such as ability to walk, or speak, or hear, etc. One can, at a given time, be suffering from a fatal disease with a limited life expectancy but not be disabled, at least at that point in time.
Yes you are. Once your cancer has spread to stage-4, it is not curable(in general). This means you are disabled for all practical purposes. Your oncologist can so state, if you request it.

Related Questions

Which treatment is out there for small brain tumors that come from breast cancer?

Srs,sgy,wholebrainrt. If they are small and few in number then either surgery or stereotactic radiosurgery may be good options. If there are a large number of them or if they are greater than 4cm in size then whole brain radiation therapy would be reccomended. Focussed radiation can spare the toxicity associated with whole brain tx and be completed in one fraction while whole brain rt is usually given over 10-15 txs. Read more...
Radiation therapy. When tumors from breast cancer go to the brain, this is metastatic disease to the brain. Options for treatment depend on the size and number and location. Surgery is an option if the brain tumor is solitary and >2-3 cm in size. If the tumors are small (<1-2cm) one can also use stereotactic radiosurgery (gamma knife, cyberknife). If there are more than 4-5 tumors, whole brain radiotherapy is used. Read more...