I know this is going to look like a stupid question, so I apologize for my ignorance up front. When I am using my fagor duo pressure cooker, how do I know if I am at 15psi? I have it set to the highest setting (number 2) which is supposed to have the max of 15psi. Is the yellow pressure indicator rising the only indication that I am at 15 psi? I've seen pictures of other pressure cookers that have lines on there pressure indicators, this one does not. Also, some pressure cookers that I have seen had gauges that showed the amount of pressure the cooker was achieving. Just wanted to make sure I wasn't missing something here.