Flame,
I've just read your last post and I know just how you feel sometimes, though my little girl is easier than yours, I think. My DD started school this year (we're in France so they start at 3) and has really struggled with social aspects (she has some sort of language disorder) and has displayed frustration at her inability to communicate. Sometimes I get really mad at her and feel like a bad mother, too, because it's not her fault and she can't express herself better, so just send you for that one because it's a horrible way to feel.
Can you organise time with just you and DD? This always helps my DD - especially if we can do something that she really enjoys, like swimming pool. I also have a DS who's only 10 mo and only just stopped b'feeding so it's been hard for DD who had me to herself for the first 3 years. Really hope that things get better soon! I'm just coming out of a bad patch myself so can really sympathise!
Brioche x