Potty Training Regression

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My 2.5yo has been potty trained since just before her 2nd birthday. She still wears a pull-up for nap and bedtime, but otherwise at home and when we go out she wears underwear. We have a pretty structured day with naturally built in potty breaks, but she will also tell me proactively when she needs to go (although this is rare.) She used to go to daycare once a week, and they wouldn’t accept her in underwear because she couldn’t go to the potty independently (she struggles with getting her underwear back on, wiping herself, and is quite short so even the child toilets at the daycare were too high for her to get on by herself) but said if she asked to go potty they would take her. Since it was one day a week we never fussed about it. Sometimes she would tell them she needed to go, sometimes she’d go in her pull up. But she didn’t have accidents at home.

Last week she started half day preschool 4x per week. Her teachers are fantastic and said to send her in underwear. But she’s had an accident every day, because she just doesn’t tell them when she needs to go. And for the last 5 days she’s doing the same thing at home too 😫 Her teachers said not to change anything, they said keep sending her in underwear with extra clothes and they’ll change her. I know regressions are normal when there are big changes, but I’m wondering if there’s anything I should do to get her back on track?