If I reset my phone would I lose everything

Depends on what type of reset you are doing.

Settings > General > Reset >

• Reset All Settings
• Erase All Content and Settings*
• Reset Network Settings
• Reset Keyboard Dictionary
• Reset Home Screen Layout
• Reset Location & Privacy

*Warning: The Erase All Content and Settings will erase all the content on your iPhone.

The other resets are safe.

If you are referring to a true reset, i.e., turning your iPhone off and on, or a forced restart, no you wouldn't lose anything. But you are regularly backing up your data?