Thank you for your help.

I can now bear weight on it while standing with crutches and for a short time without crutches. When I stand up, I can bend my leg and then lift it up, but I cannot do that while seated.
I'm not in pain apart from an occasional mild ache when I've kept my leg in the same place for a while. It's more like anxiety or paranoia... the doctor said I could go back to school and its mainly just knowing for sure what I can and can't do that's worrying me. I don't know whether I should be doing something, and the doctor would ask why I haven't been doing it/my leg would become weak, or if I really shouldn't be doing something and it would cause my leg more harm than good.

I'd like to start trying to walk, but I assume I have to be on crutches and the brace until the 4th... I also don't think my leg has enough time to heal yet. However, I'm worried for my right leg's safety (I think it was only my left leg that had problems) and when I reach behind for something, my shoulders sometimes make a clicking/popping noise. I don't want to strain my arms and legs so I've been doing the stretches I learnt in PE, but there's still two weeks of crutches to go. Walking with crutches and hopping down the stairs make me nervous since I could land wrong or put too much strain on my legs. I think my full body weight is shared between both of my arms and then my right leg while walking/climbing the stairs.

I've been looking on Yahoo Answers and many people seem to be in an immobiliser for a week or more, so I'm assuming my injury isn't as serious.
I'm only fifteen so I can't really arrange another appointment by myself and the doctors didn't seem very concerned. However, apart from the straightening knee exercise, they didn't tell me what I should be doing with my knee for the next two weeks. I'm not sure how much it can take, but I'm calmer now after having taken weight on it and raised it with no problems (except a little aching afterwards). I didn't follow RICE for three days like I did with my previous (2009) knee injury, because the doctor wanted me to be bending my knee. I stopped icing it when the pain subsided, I didn't use any compression except from the brace and it has alternated between being bent 90-180 degrees sitting down and lying flat with around 5cm of elevation.