It's tough to check the pressure regulator in the vehicle but if it is stuck, you may be able to see it if it is stuck open. The attached picture shows where the regulator is located in the valve body. There are two springs captured by the sheet metal retainer. The smaller spring and valve is your converter valve while the larger spring and valve is the regulator. Look at the regulator valve and see how far it is sticking out. you should see virtually all of the spring and a 1/2 inch or so of the valve protruding from the body.

Ideally one would drop the valve body out and split it to check but I wouldn't recommend that unless you are familiar with transmission repair.