branch practice in my project

Hi git experts,
     currently our project use git to manage source code,we only have
master branch to support development and release.However when we goes
into regression phase,code freeze will be runnning on master branch
and it will hold lots of patch in developers.

I want to use a new branch strategy  to resolve code freeeze issue

master   branch    ----1----2----3-----4-----5-----6-----7------8--->
                                     |                               |
 release                         3‘----4’---5‘                  7'----8'

our release sprint cycle is 3 weeks per sprint. when we start a new sprint,we can create a release branch and get the data back to master branch after the sprint is over

how to get the data back to master branch? I suggest we can merge release branch back, and others are afraid that merge conflict will be a big deal for us so they suggest we can double commit into master and release branch

what's your thoughts? Could you give me some suggestions?

Thanks in advance

Lynn