My MacBook pro Wi-Fi is slow, other devices are OK
Your MCS is zero (0) which would explain why your WiFi is slow.

That can happen if there is channel crowding (not only from your devices but neighbors included).

You could just change the channel for now 1 to 5 and try.

Or you could do a quick analysis of the channels do following:

In Spotlight type "Wireless Diagnostics"

Click on Wireless diagnostics to start it.

Now in the menu bar click on the Window - Utility - WiFi scan -Scan Now.

Sort the result by channel so you can see how crwoded are the channels.

Open your FritzBox set up page and set it to the least occupied channel.

If you do not know how, open any of the following  Internet Explorer, Google Chrome, Mozilla Firefox, Safari.

In the address window type 192.168.178.1 , that should open the FritzBox set up page.