colditz, I LOVED what you said in your 4.40pm post about toddlers! perfect description and I think we all need to hang on to that idea, that how they behave is not really a reflection on their parenting at this stage!!!!!! You have summed toddlers up so well.
Hearts, if it helps you are SO not alone. I think all mothers must feel like you and it is very very hard to keep going five days a week as you say. I feel exactly the same with my three and a half year old - he will be slipping off to school this year and I can't believe how quickly it has come to this stage, but there are still days when I can't do a thing with him. I think it has helped me to accept that toddlers can't be 'controlled' so I would say forget this idea and take the pressure off yourself! All you can do is provide plenty of play and diverting activites, and strong boundaries for what is and is not acceptable. Then really you can do no more. If you can remain calm and take time out when she's being impossible, then you lose that feeling of them controlling you and start to feel in control a bit more.
I feel exactly the same about not being able to get things done in the day. I have always spent the majority of time with my son, not on housework etc, and it means lots of stuff gets put off till evenings, which is draining and tiring. I just tell myself that this isn't forever - they don't want all your attention forever.
Pre-school is brilliant too, as there definitely comes a timewhen the stimulation at home, no matter how attentive and imaginative the mum, seems no longer to be enough and you drive eachother mad! This has improved since my son has started pre-school - he appreciates home a bit more for being out of it sometimes and gets huge levels of mental stimulation not just from the activities but from the effort of leaving mum for the first time etc. I'd say use pre-school as a break from eachother and don't feel bad about it!
Though all the play and attention with me seems to have made my son very clingy to the pre-school teachers, but think I'll start another thread on that!
Good luck, you are doing a fab job. It IS hard and most mums feel just the same as you!