Buy a hydraulic test kit (expensive) or get 3k pressure gauge and the fitting to match your tractor's FEL quick connects.... or you can "T" this into your system.
On what are you basing that assessment? Hydraulic pressure gauges are inexpensive and easy to install in the pump circuit. You can install a JIC tee on the inlet to your loader valve and use it as a test point. Keep it capped when the gauge is not connected. To get a pump presure reading just roll the bucket back hand hold it there with the control lever. That will block the pump flow and deadhead it against the system relief.