@sophie93, I am a patient and have had a liver transplant. Thus my experience is the limit of my knowledge about liver enzymes. I can see that your doctor has already ruled out some of the common causes of elevated liver enzymes and I assume that you are not taking any over the counter meds or supplements and herbs without your doctor's approval because these can affect your liver function numbers and cause damage to your liver. The same can be said for drugs and alcohol.
Nearly 20 years ago, my liver enzymes were elevated and I was referred to a Gastroenterologist, and was eventually diagnosed with a rare liver disease that was (and still is) mostly unknown to most providers.specialists.

Are you under the care of a Gastroenterologist? Are you being monitored for the increasing liver enzymes?

Elevated liver enzymes
https://www.mayoclinic.org/symptoms/elevated-liver-enzymes/basics/causes/sym-20050830