Was your Antivirus enabled while performing the scan? That can impact your test results as Anti-virus often scans inbound and outbound network traffic for malware. This is very processor intensive.
The other part is your browser. Some speed tests are limited by your browser, since some speed tests have to write to your disk as part of testing download speeds. Upload speed testing is also processor intensive, since speed tests are designed to generate data that cannot be compressed, so it gives an accurate result. Try the Ookla speed test app from the Microsoft Store or Apple App Store, as it can help rule out your browser.
Try the Verizon speed test, and if you have a Verizon router like the G1100 or the G3100, make sure it is plugged in first before running your speed test on Verizon's site. Pay attention to what you see for the "Router" Speed test result. This helps to prove whether or not the problem is with your computer, or with your connection as a whole.