Once again I have been driven to despair and tears tonight over my 8 year old's behaviour tonight 
She is the youngest of three girls, older two are nearly 14 and 12. I know it's hard for dd3 being the youngest after a 4 year gap, and older two dds are very close. But her behaviour is dreadful and is like that of a much younger child IMO.
She has a terribly short temper and will lash out both physically and verbally when she hears something she doesn't like. She seems to have no self control. I have explained over and over again we DON'T hit/kick/push people WHATEVER the circumstances and she is old enough now to explain with words what is bothering her. I do try to use time out for physical aggression but it's hard in a public place or in the car.
She also cries a lot. Over the slightest thing, like a toddler. Long, drawn out crying and whining that does your head in. I have lost my patience on many occasions, she brings out the worst in me and I feel so unlike the mother I set out to be 
She complains so much about minor matters, it makes her sound like a spoilt brat. Something is always wrong - her toast is buttered enough, her clothes are uncomfortable, her shoes are done up wrong etc. Whine, whine, whine.
I feel I've failed her and failed as a parent. Although older two dds are lovely and generally very easy and well behaved so I must have done something right. I try VERY hard not to pigeon hole dd3 as being 'the naughty one' as I know it's a self fulfilling prophecy. And dd3 CAN be totally delightful. She is very sweet and loving, very attached to me, very physically affectionate, loves cuddles etc. When she's in the right mood she is very lovely and I really enjoy being with her. She has the luxury of being my only child still at primary school so enjoys my uninterrupted attention going to and from school every day.
It feels like I've been waiting and waiting for her to improve with age and she hasn't. She's now 8 and sometimes I feel like I'm dealing with a 3 year old. I just don't know what to do any more 