This honestly sounds normal for your age. Doesn't sound like anything to worry about. Should regulate as you age and reach your 20s.
No this isn't my first menstrual cycle and no I am not sexually active.
They can. I used to bleed for months on end with mine and then skip for just as long. Is this your first menstrual cycle, or have you had any previously before this? And are you sexually active?
a period lasting 17days?? that doesn't sound normal...id go check with a doctor. i dont wanna worry you honey, i just never heard of even an irregular period lasting that long without something being amiss.
At your age this can be normal. Some periods are likely to be light, and others heavy. You could also expect it to show up irregularly, so it could show some months and others not. It will regulate itself as you get older.