混淆git分支和主交互

I am working locally. I checked out a branch "b1" and did some work on it. I want to keep the branch "b1" the way it is but go back to the master and for it to be like it was before I checked out "b1". But when I check out master with "git checkout master" all the changes I made in the branch are already in the master without any commits or merges. What am I doing wrong?I am working locally. I checked out a branch "b