Growing up isn't easy and having dark hair anywhere on your face certainly doesn't help.
I know you said that you aren't allowed to wax or bleach. I assume this is because your parents won't let you. That may have been the answer before, but why don't you try asking again. Explain how people at school are talking about it. I'm sure you have trouble concentrating on our school work because you are worried about what others think. I'm sure that once your parents hear your pleas and how it is affecting your school work, they will help you take care of the problem. Just be open and honest with them.
When I was your age, I had the same trouble. I have tried all different types of methods and all of them cause a little bit of pain. If tweezing is your only option, just know that it will get a little easier. With your parent's support and supervision, ask them to check with the pharmacist who might be able to get you some numbing cream which would make the tweeting a little less painful. They will only sell this cream to an adult, if the drug store has it.