When installing Python with MacPorts things are a little different. First check if you have the correct Python version installed.

$ port select --list python
Available versions for python:
    python27 (active)

This output demonstrates you don’t have the correct version so do a:

$ port install python34

Next you want to set the correct default version:

$ port select --set python python34
Selecting 'python34' for 'python' succeeded. 'python34' is now active.

In order to get pip up and running download and set pip as well:

$ port install py34-pip
$ port select --list pip
Available versions for pip:
    pip27 (active)
$ port select --set pip pip34
Selecting 'pip34' for 'pip' succeeded. 'pip34' is now active.

Nearly there. Now set the correct path since MacPorts does not install python3 under /usr/local. But thats simple:

$ which python
$ which python3
$ export PATH=/opt/local/Library/Frameworks/Python.framework/Versions/3.4/bin:$PATH
$which python3

That should do it.