@TDR
There are programs/apps for various operating systems that can show you exactly what is using data on the device. Glasswire is often recommend for Windows based computers. The free version is good enough, and it works very well. It will tell you not only how much data the computer it's installed on is using, but just what on that computer is using it, and how much each program, app and/or process is using during the specified time period.
Glasswire is also available for Android devices, though I've never tried it on mine, personally.
It's a good idea to install an ad blocker in your browser. I use Adblock Plus, which works with the Chrome variants (Edge, Blaze, etc) and Safari. Make sure to go into its options and de-select "Allow acceptable ads" or you'll still see them, wasting data.
If you stream, that can use a lot of data. Using Netflix as a common reference, it uses around 3GB per hour in HD, 700MB per hour in SD and 300MB per hour in LD.
If you use streaming devices, such as an Amazon Fire Stick, make sure that all "auto" things that might use data are disabled.
If you have a DirecTV receiver and it's connected to HughesNet, sever that connection, as that could very well be what's chewing through your data. DirecTV receivers will use internet data instead of their own to update many things on the receiver, and it can use a ton of it to do so. Because of this, connecting a DirecTV receiver to HughesNet is recommended against.
It's also best to avoid using cloud storage, especially when it's set to automatically save.
If you use Windows 10, it's best to avoid using Update Optimization, unless it's only on your own network, which can then be a benefit. If you don't share updates with other Windows 10 devices on your network, it's best to have this off completely.
Lastly, the following two topics contain some helpful information. Some of it's already been touched on here, but there is a lot of good information...
https://community.hughesnet.com/t5/Tech-Support/HughesNet-Data-Management-Tips-n-Tricks-How-To-Elimi...
https://community.hughesnet.com/t5/Tech-Support/Understanding-data-usage-data-loss-and-connection-pa...
