Is your site responsive?
This tool will help you test the breakpoints in your site.
bower install rnowm/bp-inspector
In index.html
replace <iframe id="iframe" src="demo-site.html"></iframe>
with the path to the file you want to test.
Then add the breakpoints you need like so:
<script>
var breakpoints = { 'SM' : '768',
'MD' : '992',
'LG' : '1200' }
</script>
See a demo here.