To feel fed up

[YukoandHiro]

Had a rubbish day for loads of tedious reasons but to top it all off, I picked DD up from nursery to discover she'd refused the potty all day and just constantly wet herself. She now has terrible bum rash from obviously being left longer than ideal in wet things.
We've been training almost a fortnight and were down to about one accident a day before this. She's 2.5 if relevant.
How long can I expect this regression to last? I thought regressions occurred later after being fully dry? Or this is about her boredom/gaining control again?
Any ideas. So fed up although obviously just being super positive About the hits and ignoring accidents.

She might be more nervous about using the potty at nursery than at home. Could you try having her use the potty with you there at nursery at drop off?

She has been fine there the last week or so... but will try that tomorrow

Iv always gone with of mine arnt dry within the week then put it on hold for couple of months and try again.

Problem is she now outright refuses nappies except at bedtime as she loves her big girl knickers.
Think we're in for a long haul...