So i have a theory. Everyone has been saying the Beast was 11 when the enchantress cast the spell on him, but the prologue says “…Until is 21st year”. Which obviously means birthday, but maybe he was already 21 and time froze everyone in the castle’s ages. And the rose would bloom until his 21st year of being a beast?
This makes sense! Mrs Potts did not seem to be in distress over the fact that she suddenly had a child that was younger than 10 years of age :)