Two years without a period

Patient: My 25 year old daughter stopped having her period after taking Yaz birth control pill for a couple of months then quiting. It has been 2 years without a period and she has seen 3 different doctors who don’t seem to be too concerned and don’t have a answer why she isn’t. I understand that Yaz by Bayer is being investigated. Do we need to be more concerned about this than the doctors are she has seen?