For the first ten or twenty days of service, depending on you plan and modem, your data resets daily, so it's more or less unlimited for those days. This would explain why your first month went so well.
You should check your usage daily, or even more often.
This may help...
Following the steps could help you to find out where your data is going.
Hughesnet is not amenable to constant streaming, but it can be done within reason.