Do i need to lose weight? And if so, how much? X?

Hi, Well i am 13, and i just feel so fat around all my friends! I am 5'4 ish and i weight 145 lb or 10 stone 5' and i just wanted to know if i am too fat or like average! And if i am too fat how can i lose weight? Now that thee summer holidays are here it gives me time to lose weight! All of the boys at school call me fat and it just brings me down! And i thought that if i do lose, weight than it will just show them! I wanna be like thin so maybe like 9 stone sumthin or even 8 stone sumthin! But the trouble is, is that my mum cooks all my food and she does me like kinda like nearly full plates and unhealthy food and i am too scared to ask her for less! Buh i just wanna lose weight! So any help is really gratefull! Thaanks for reading! X