An update.
I couldn't use any commands in the Terminal and believe me I tried.
I erased the disk and installed a new OS X Sierra and the first thing I did was to buy Trim enabler 4. I enabled it and it worked without any problems and under the button "about my computer" it now says Trim support: YES.
I also did a benchmark. I don't know if this is a good result cause I forgot to do a benchmark before I enabled the trim lol.
Thanks for all the advices guys!

Skärmavbild 2019-01-08 kl. 20.21.06.pngSkärmavbild 2019-01-08 kl. 20.21.06.png