You do have a separate partition for /boot. It is tiny (237 MB). You need to
enlarge it. 1 GB would be OK if you regularly remove the older kernels. You
must use a Live system take space from other partitions (the root partition I
guess). Trisquel's live ISO includes GParted, which makes it quite easy to
resize partitions.
And your user data are on the root partition. That means you cannot change
the operating system while keeping those data.
Were all those choices carefully thought? If not, what about a reinstall
(after a backup of the user data and of the list of installed packages)
keeping the default partition schema?
