For what it is worth, here is an idea that makes the navbar items morph from text to an icon based on the current responsive size.
<li><a href="#contact"><div class="hidden-sm">Contact<b class="caret"></b></div><span class="glyphicon glyphicon-plus visible-sm"></span></a></li>
The result is the ‘Contact’ text converts into a plus icon at small size. Here’s a bootply example