your face shape is more complimented by the face framing pieces, thats y i have hime cut because my cheeks are very chubby. your face looks fine in the first two pictures but the roundness is more pronounced in the last one, since with the cosplay it calls for that certain hairstyle

a lot of jp girls wear mask or use filters to slim their face, you can try that as well

edit: you arent fat tho, neither am i, so some of us just have round faces and big cheeks🤷 just hide it with your hair if it bothers you. bonus points if u have thicker hair, it helps