How do i use my MacBook Pro on iPhone hotspot?
Simply turn off the Wi-Fi on your iPhone, and share your cellular connection through USB cable from your iPhone to your Mac.

If you don't otherwise need the crappy Wi-Fi network you have, just turn it off, most probably on your Internet connection router.

To improve the quality of your wireless environment, and if you don't use it to access your iPhone, I advise you to turn off Bluetooth on your iPhone too.