Why I am unable to switch bash to the one installed by homebrew

I'm trying to update bash to version 4.x. I did brew upgrade, then brew update, then brew install bash. I ran sudo bash -c "echo /usr/local/bin/bash >> /etc/shells" and sudo bash -c "echo /usr/local/bin/bash >> /private/etc/shells". I've tried symlinking /usr/local/Cellar/bash/4.3.32/bin/bash to /usr/local/bin/bash. I've closed Terminal.app. I've even logged out of Mac completely. Nothing I do has updated $BASH_VERSION to the right thing. bash --version does say the right thing, but I think I read somewhere that that is less reliable then echo $BASH_VERSION (maybe). Here's a summary of what I'm seeing:

I just need to know . . . what version of bash am I actually on? And if it's not 4.x, how do I reliably, definitively make it that?

I am on Yosemite FWIW.

Edit:

$PATH was too long for a comment. Here it is:

/Users/AndrewNichols/.rvm/gems/ruby-2.1.1/bin:/Users/AndrewNichols/.rvm/gems/ruby-2.1.1@global/bin:/Users/AndrewNichols/.rvm/rubies/ruby-2.1.1/bin:/usr/local/heroku/bin:/usr/local/opt/coreutils/libexec/gnubin:/usr/local/Cellar/grep/2.18/bin:/usr/local/opt/gnu-sed/libexec/gnubin:/usr/local/opt/gnu-tar/libexec/gnubin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/opt/X11/bin:/usr/local/heroku/bin:/usr/local/opt/coreutils/libexec/gnubin:/usr/local/Cellar/grep/2.18/bin:/usr/local/opt/gnu-sed/libexec/gnubin:/usr/local/opt/gnu-tar/libexec/gnubin:~/activator:/Users/AndrewNichols/sonarqube-4.5/bin/macosx-universal-64:/Users/AndrewNichols/sonar-runner-2.4/bin:/Users/AndrewNichols/bin:~/activator:/Users/AndrewNichols/sonarqube-4.5/bin/macosx-universal-64:/Users/AndrewNichols/sonar-runner-2.4/bin:/Users/AndrewNichols/bin:/Users/AndrewNichols/.rvm/bin

Here's one split on colon, for readability:

'/Users/AndrewNichols/.rvm/gems/ruby-2.1.1/bin',
'/Users/AndrewNichols/.rvm/gems/ruby-2.1.1@global/bin',
'/Users/AndrewNichols/.rvm/rubies/ruby-2.1.1/bin',
'/usr/local/heroku/bin',
'/usr/local/opt/coreutils/libexec/gnubin',
'/usr/local/Cellar/grep/2.18/bin',
'/usr/local/opt/gnu-sed/libexec/gnubin',
'/usr/local/opt/gnu-tar/libexec/gnubin',
'/usr/local/bin',
'/usr/bin',
'/bin',
'/usr/sbin',
'/sbin',
'/opt/X11/bin',
'/usr/local/heroku/bin',
'/usr/local/opt/coreutils/libexec/gnubin',
'/usr/local/Cellar/grep/2.18/bin',
'/usr/local/opt/gnu-sed/libexec/gnubin',
'/usr/local/opt/gnu-tar/libexec/gnubin',
'~/activator',
'/Users/AndrewNichols/sonarqube-4.5/bin/macosx-universal-64',
'/Users/AndrewNichols/sonar-runner-2.4/bin',
'/Users/AndrewNichols/bin',
'~/activator',
'/Users/AndrewNichols/sonarqube-4.5/bin/macosx-universal-64',
'/Users/AndrewNichols/sonar-runner-2.4/bin',
'/Users/AndrewNichols/bin',
'/Users/AndrewNichols/.rvm/bin'

Some of the duplication there is because I have terminal set to run tmux on startup, so .bashrc gets sourced twice.