My 17yr old daughter has had periods for 4 years now and they are every 2 weeks and last for 9 days.
She is getting fed up with being on so much.
I don’t think this is normal and would have thought they would have settled down into a regular pattern by now.
Should I now contact a Doctor?
yes. Life is variable and so are people. but "bi-monthlies" aren't the norm and it sounds as though they're messing up your daughter's life. Give your GP a call (or however you make contact these days).
Has it always been on this schedule? As a teenager, an irregular cycle is not uncommon, and this may be normal for her body. Thought it does seem rather unusual.
I'd still recommend seeing a doctor.
Post puberty, young girl, multiple and prolonged periods sounds typical of what is known as Abnormal Uterine Bleeding, the commonest causes are thickening of the uterine wall and fibroid.
Depends how she feels, if she gets dizzy spells or feels faint and the bleeding is heavy, then she should seel medical advice.
If she isn't particularly inconvienced then should could monitor the situation for a few months.
The choice must be hers.