Toddler has nickname we didn’t choose at daycare, wwyd?

Hi all, don’t know if this belongs on this sub, but this place has been helpful for me!

My 2-year old has a family name (used on both sides) — Miriam. Another member of our extended family is also named Miriam, but she has always gone by Mimi. So we thought (and all discussed) that it would be great as long as we didn’t use the same nickname. Easy! Right?

We call her Miriam at home, but the other toddlers at school started calling her Mimi (the R is hard). And the teachers have picked it up and now pretty much everyone at school uses it. I let it go thinking that when she got old enough, she could choose her own nickname. But recently she’s been correcting us at home when we use Miriam. Mimi is a very cute nickname, I know! But it’s just not what we chose for her.
I fear that the time for correcting it has passed.

What would you do in this situation? Let it go? Keep calling her Miriam at home? Or try to correct it?

EDIT::

Yes, yes, ok. Of course you are all so right! Thank you for the bit of perspective. I knew i needed to let it go, but I think I’m still so close to those 9 months we spent agonizing over what to name her, haha. As you all suggested, we are going to lean in! There is also a kid in her glass that they all call JuJu and I know his parents didn’t choose that nickname!