Attention seeking behaviour instead of words - what to do?

[Woollymummy]

DD is very capable at talking about everything except needing the loo. She is 2 and a half. We have tried lots of approaches but she still will go off, be quiet, squat down, do a wee or a poo, often after hous of being dry and clean, and not say anything. However, she comes up for a cuddle, comes for a story, comes to show me her fave toy etc, etc, or more recently starts doing something naughty like try to climb on Daddy's office chair, lick addresses off envelopes, play with things she isn't allowed etc. What should we do?

I meant to say that all of the sudden cuddliness, demanding a story, climbing on my lap etc, or playing with stuff she shouldn't happens because she has just done a wee or poo, and she knows that when she comes over I will inevitably check her nappy. If I don't no-one else seems to (DP and MIL NEVER check, and she gets rotten nappy rash if poo left on so I check very often). Should I stop checking? Is that part of the problem - she knows I will check so she has never bothered to learn how to ask to be changed. I can't bear to see her bum sore, but if that is what it takes....