Hi bb360,
Try creating a new event on your Mac. Then try syncing your iPhone with your Mac. Does the test event go to your iPhone?
On your iPhone, go to Settings > Calendar > Accounts. Which accounts listed there have Calendars enabled?
Let's also check the settings on your Mac to find out if there are any calendars syncing to your Mac. Click the Apple Menu > System Settings. Select Internet Accounts on the left. Which accounts are syncing the calendar events?
You can also verify the syncing settings on your Mac and make sure they're set correctly. Here's how:
"Sync calendars to your device: Select the “Sync calendars onto [device name]” checkbox, then click “All calendars” or “Selected calendars.” If you clicked “Selected calendars,” select the checkboxes of the calendars you want to sync in the Calendars list. "
This information is from Sync contacts and calendars onto your Mac and iPhone, iPad, or iPod touch - Apple Support.
Take care.