What are possible causes of constant pressure towards the back of my jaw?

Wisdom Teeth: At your age it is not uncommon to have a sensation of pressure in the back part of your jaw. Sometimes just on one side or both sides. I would ask your dentist to take a panoramic xray . Most of us do not have enough room for wisdom teeth and they need to be removed. The earlier the better. Age 16 for a girl is perfect. Usually an oral surgeon or highly trained gp will remove all 4.

Wisdom teeth: Likely wisdom teeth at your age. Also possible TMJ dysfunction if joint pain, joint noises, clench/grinding. See oral & maxillofacial surgeon for diagnosis/treatment.