You're really not giving her enough money, if you can afford to give more.
If you can, you should be providing far more than you are.
If you aren't, you need to educate her and discuss with her.
My 14 year old gets £30 a month, of which she has to save £10 for gifts for family for birthday presents and Christmas presents.
When out and about, we buy her food and drinks. People seriously underestimate how much teenage girls need to eat (based on my sample size of me at that age, my girls and their friends). Especially if they've hit their periods. That being said, if we go for a one hour walk, no no snack is required. If we are out for 3 or more hours not including a meal, we'll get a snack. But if I couldn't afford that, I'd take one from home.
Her hair, well I wouldn't be letting her bleach it, but as you do, you should have considered the cost implications first.