@anlytcphil I'd like to reaffirm what others have said here, that having good communication with your toddler's daycare teachers is the most important thing (so at least they know to respect her multilingual background), and add some personal experiences.
Our daughter is 25 mo. old and just entered a Colombian daycare in which they only speak Spanish, after 2 years of being raised in a combined English-Spanish environment at home (we both speak both languages so not OPOL, lots of native English interaction with me).
-Not sure how things are where you live, but around here, an adult will *never* scold or correct our little daughter when she produces words the adult doesn't understand. Sometimes it's because she says a word in English when Spanish is dominant here (e.g. "bubble"), but many times she (like all toddlers) has an idiosyncratic word that she made up for something, e.g. she calls all dogs "coco" (nothing to do with the Spanish words, "perro" or "cachorro", for the concept).
When our 2-year-old says a word to an adult outside the household which they don't understand, at the worst she gets a blank stare, or maybe they ask us "Did she say 'coco'? What does she mean?" Adults (and especially day care teachers) seem to just go with the flow and figure out what she wants to say without ever explicitly "correcting" her (which, as I understand, is a very sound approach for teaching kids language(s)).
-In spite of hearing lots of words for things in two different languages all the time, our daughter just picks one word for each thing / concept in each langue and stubbornly sticks with it. There's no clear pattern, e.g. she says some colors in English ("blue" and "purple") and others in Spanish ("(r)ojo", "verde"). Hearing adults use different words for these things every day has done nothing to dissuade her and she has stuck to "one concept, one word" for now, with no replacement of English words by Spanish or vice-versa. But perhaps this has to do with the personality and particular development style of my daughter.
-In case you're still worried that your toddler is losing Spanish, you should try reading a picture book with her and ask her things (e.g. "¿Dónde está el OSO?", and she can at least point if she doesn't want to say the word). We do this a lot so I am %100 sure that my daughter knows what "cat" means even if she only ever says "gata" for kitties.
Good luck! Kids are amazing at sorting these things out and nothing you've said here seems a cause for worry.