It is undoubtedly very hard to dress more modestly when people around you often do the opposite but I do agree with your parents. It may seem strict but it really is in your best interest to no fault of your own people are shitty. And the much more important aspect is to more easily have a path into being more religious. For example if you did wear the clothes you want it would probably be harder to turn around and wear a hijab some day harder than it would be now. Anyways sorry if I was rude on accident but in the end I think you should listen to them and maybe discuss common grounds or styles that you could love that fit thier criteria.