Welcome to the forums andjeladavidovic !
Please try this first -
This will purge the proprietary "wl" driver that is currently in use, so that the native "brcmsmac" module can load instead since next boot. Reboot and see if you can use your wifi.
sudo apt-get purge bcmwl-kernel-source
If not, please follow the "Wireless Script" link in my signature, download and run the script as per instructions there, and post back the report it generates.
While posting the outputs, please use 'Code' tags. It preserves the output's formatting and makes the post cleaner, compact and more readable. To see a quick 'HowTo' with screenshots, please follow the "Using Code Tags" link in my signature.