How can I figure out why my water pressure is basically zero?
Check your hose bibs outside the house, those typically are first in line.  If those are low pressure then its before your house.  If those are good, then it's in your house.  As for water company checking pressure, what they said is correct.  They just don't install the monitoring equipment to do that.  They will install pressure gauges at key points in the distribution network but that's it.  From water main to your house there will be no way for them to check.

Also, check your water meter.  If its spinning with no visible water use then you have a leak.