Am i too late to get the flu shot if everyone else in the house is already sick?

No: It's too late to get the flu shot if you already had the flu, not if you or people close to you are "already sick." too many people think getting a flu shot is supposed to stop you from getting sick. It does, but it only stops you from getting sick with the flu, and nothing else. There are many, many illnesses, and the flu shot protects you from the flu.

Yes & no: If they all have the flu you have likely been exposed enough to get that strain. It takes 2-3 weeks for the shot to stimulate enough protection to stop a flu. You can still get the shot, which could protect you from other strains later on. If any of them have flu your best defense is antiviral meds. (Tamiflu can help you stop or make it less intense)