At my wit's end

I know there are probably a million reasons to not worry about this but here goes.

Kate had a terrible potty week at school. Three days this week she pooped in her pants. She stopped pooping in her diapers, for crying out loud, when she was 15 months old. We had maybe 5 poops in her diapers after that time. She asked for underwear at 23 months. When she is with us, she doesn't have accidents anymore. She pees on the potty at school just fine - UNTIL today...two pee-pee accidents at school today. One I understand b/c it was at nap time - sometimes she wakes up and just pees. The other time I don't get - she just stood in the middle of the classroom and peed like nothing was happening.

Last night and this morning I talked to her about using the toilet. She seems to understand, says "ok", etc. I asked if she wanted diapers or underwear and she said "underwear". Sometimes I wonder if the unpotty trained children at school confuse her. She will come home and say things like "I smell something. Let me check you for poop." and will try to pull the back of my pants down. She asked me yesterday if I poop in my pants - I told her "no, mommy poops on the toilet."

It makes me feel so guilty b/c it seems all school related. I know I can't just take her out of school b/c I hope to be working soon but then I wonder if we put her in school too soon. However I like her in school - I am the most sane I've been in a while (most of the time).

What do I do, if anything, to help the potty situation? I am afraid her teachers will tire of all this and ask to put her in diapers. I do NOT want to go backwards. Help!