Ok, you assigned quotas to the /(root) mount but your data is stored on the /home partition. Change your fstab to the following:
First, start by editing your fstab so the proper mount point has quotas assigned.
/dev/sda2 / ext4 defaults,relatime 0 1
/dev/sda3 /home ext4 usrjquota=aquota.user,jqfmt=vfsv1,errors=remount-ro,relatime 1 2
/dev/sda4 swap swap defaults 0 0
Next, turn off and reassign quotas to be read from the correct mount point.
service quota stop
mount -o remount /home
quotacheck -auMF vfsv1
quotaon -uv /home
service quota start
fix-disk_widget_home to adjust the dashboard disk widget to read the right mounts.
You'll also want to tun off the plugin
diskspace and then turn on
diskspaceh on your dashboard (under the plugin tab) on the left menu.
This should set you up with a fix.