You want to lay the blame on girls at school, but that’s not right either. The problem is that you are looking.
As a girl, I actually totally disagree with Irishmom, and I commend you for your mature response. I don’t believe that you are fully laying the blame on the girls at your school, you are simply stating that you find it hard to fight against lust when you see girls dressed that way. That is actually a completely normally male response.
Fashions may have changed, but the way that men are wired has not changed. God created men to be visually stimulated by the beauty of the female body. This is a good thing, a beautiful thing actually, to encourage nuptial love and procreation.
Unfortunately in today’s world, men now have visual access to women’s bodies outside of marriage, due to immodest fashions, pornography, etc. With the fashions of today (tight yoga pants, low tops, mini skirts, that kind of thing) so many good men struggle with where to place their eyes. They shouldn’t be picked on and abused when they state that they struggle to maintain purity when a girl is dressed a certain way! It is only natural that they would have those thoughts/feelings! However, men should never goggle at a girl like she is eye candy for their own pleasure (which you are not doing) and if they do feel tempted, they should always fight against the desire to look and any thoughts that arise (which is what you are doing, well done, and keep doing this).
A lot of women today are angered when men speak about fashion and lust, and state that they can dress however they want, and men shouldn’t lust after them. This is flawed thinking though, because of how men are designed! Maintaining and upholding purity in a society is a two-way process, where both the men and the women have important roles. Both should strive to obtain pure hearts and minds through prayer, both should avert their eyes if necessary, and both should dress and act in ways that are modest. And no, I don’t mean that women have to be covered from neck to ankles, or wear a full burqa or anything like that
Just dress in a way that highlights that we are daughters of God, and that our bodies are worthy of respect. Men should do the same!
In a society where all men and all women do not fully commit to purity in these ways, it can make it harder for those who are committed to purity.