Question about my eyesight...?

I'm 11. During my summer (here in my place, summer is on March to May/June), I used the computer all day, every day. I sometimes take breaks. When my classes started, I noticed that everything was so blurry from my seat in the back of the room. I found this weird at first because in the past school year, I could see properly from the back. Anyway, it was quite blurry, but I can still read the stuff on the board. Recently, my teacher moved my seat to the 3rd row of the room and I can see a bit better now, but the problem is that my vision is still a bit blurry. Am I near-sighted or what?