From what i know about Trigeminal Neuralgia, having had it for over 6 months now.. is that the pain varies from person to person. Typically it is felt on one side of the face (usually the right) and is an electric shock/ shooting type pain which is very painful. The pain lasts for around 30 seconds. You can get regular attacks or infrequent attacks.
I believe there are two types of TN though.. the other being the more constant pain which you described.
I was diagnosed by a specialist at hospital after i initially responded well to a drug called carbamazapine. This is usually how they determine whether you have TN. There are other anti seizure drugs they can try you out on to see if it helps with the pain and if it does.. it can usually indicate that you have TN.
Also.. if it is the most painful thing you have experienced (9 OR 10 on the pain scale).. then that is also another good indication that it is TN.