Sounds like the guy you talked to is on the right trail. If you don't have a big leak or high consumption then there is something blocking the oil flow or leaking back the the sump before the filter.

Pull the valve cover and be sure the oil rail is spraying on the cam lobes and not cracked/broken. If that is good then its time to drop the lower oil pan and have a look at the pump, relief valve and shaft bushings.