Phone storage woes

[KnitMeAUnicorn]

I got a Galaxy J3 about a month ago and started putting apps on it. It quickly got full up so I bought a little SD storage card and I started moving apps over.

However, with many of the apps I'm not given the option to transfer them to the SD card for some reason –it's greyed out. So basically I have a 28GB storage card and only 2GB is being used, while my 8GB phone is almost completely full and I can't even do software updates!!

Anyone know why this is? I don't think I have that many apps installed –only Spotify, Facebook, Outlook, Messenger, a couple of running apps, Tesco Groceries, the Guardian and Instagram. That's not loads, surely?!

Help!