1 - Probably the 16 GB SD it's not compatible. It's better to backup whatever you need from SHARE partition and start all over again. And...
2 - Why you cannot resize the partition with Gparted? You have that fsck "metadata_csum" error? If so, you should use a much more updated liveCD distro for the fix. In my case, i use the latest "Linux Lite" distro and no issues. That OS is just a recomendation, you can use whatever you want, but always the latest version for max compatibility. Before that i use a much older Ubuntu 14.04 LTS-based distro and that error jumps up.