I have a similar issue with not getting calendar notifications for events I put on my Google calendar. I logged into Google on my PC and there is an option in the calendar to set up a mobile device for notifications. My next calendar appt is Thursday at 6pm and I have the reminder set for 2 days. We’ll see if I get a reminder tonight at 6 pm.
You should check your notification settings in your Gmail app. Make sure the box for email notifications is checked and also, tap the “labels to notify” box and make sure the settings in there are what you want them to be.