Hi Katrazena!
I was 16 (21 now) when I was diagnoses so I truly understand how you feel about school and all that stuff, don't worry thought, you'll ge through it and I can guarantee it will make you a lot stronger!
As for side effects, I can only speak about Methotrexate, which is what I am on and have been since the start. At first I suffered quite badly from feeling ill (being sick) and tiredness, I think it took me about a year to start to feel better. The best thing is to try and take your dose on something like a Saturday, that way you can spend Sunday resting and hopefully feel better on Monday when its time for school.

Regarding hairloss, I don't think you have to worry, the doses given are usually not high enough to cause hair loss, however you might notice the quality of your hair change and it might become a bit thinner, but you shouldn't lose your hair.

Take care!