I felt uncomfortable for a while when I started secondary school because I was not wearing a bra and my chest, though small, was obvious. PE was uncomfortable without one. Eventually my mum gave in and brought a bra back from the weekly shop. I didn't fit into the 28AA she'd bought but the next week I fitted into a 30A. I felt so much more comfortable after that about my development. I don't feel embarrassed because I was developing, but because everyone in my class was more covered up than me.