I had GAD too. My periods were long, 7 days. You haven't changed type of tampon or pad have you? I switched to the "new" (at the time) super absorbent tampons before they knew they caused toxic shock and that increased my period length and mildly made me ill so I stopped them pretty quick (only used them for one or two periods). So if you changed anything in your routine, I would go back to what makes you comfortable and what you know.

The length of time is not too important when you are young, especially if you were messing with your diet/how much you were/were not eating. Yes, stress can mess with that like it messes with your head too, makes you more anxious? I use to get almost suicidal a day or two before my period and the week of. Reminding myself of that (that it was only that week or two) did not make me feel better but it helped me wait it out.

If I were you, I would go out and find myself a decent meal with meat, vegetables, the whole deal. Your body definitely needs nutritional support and that you don't have to go to anyone for, you just have to do it. Without it, the GAD gets worse and it becomes a bad cycle you don't want to be part of (as in cyclone :-) Without the nutrition you could get really sick, not just worried you are or are getting so.