A better indication is to look at the data usage section on the phone itself rather than the generalized info on My Verizon. Be sure to change the phone's reporting period to match your VzW billing cycle.
I know I like to keep track of what I'm using my data on also. Please go to the app, and scroll to Troubleshooting and Data management. You will find the Data Utilization tool very useful. https://www.verizonwireless.com/support/data-usage-faqs/
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