Unjust PA situation

I'm a year 13 who takes BTEC performing arts. Our teacher has picked out the musical we will be performing in order to be graded on (I won't share it in case it gives me away.) None of us were happy with her decision, as the musical she chose has two male protagonists (we have no males in year 12 or 13.)

When the cast list came out a week ago, I was shocked to see that although myself and other members of our year had gotten main roles, we were sharing them with year 11s. These year 11s aren't doing A-levels, but out of the 8 shows we will be performing they will perform 4.

Boy 1 = Oliver (Year 11)
Boy 2 = Jamie (Year 11)
Girl 1 = Lisa (Year 12) and Annie (Year 11)
Girl 2 = Me (Year 13) and Madi (Year 11)
Girl 3 = Bella (Year 13) and Madi (Year 11)

I find it unfair that year 11s (who aren't even taking the A-level) have received main character roles. Myself and Bella are the only year 13s to receive main roles, with the 5 other year 13s being given ensamble, and the 14 year 12 girls also being put in ensamble.

I'm here to ask everyone (from an outsiders perspective) if this is right - I feel like what my teacher has done is wrong.

Thanks, S

Why does your teacher have to cast boys just because the role is "male". I've seen fantastic productions at drama school where casting was switched compared to the norm. In The Taming of the Shrew for example ,every part was gender reversed.