DD is an only child and is 6 years old; she has always been highly strung but I'm beginning to think there's something not "right" more and more.
I've spoken to school who said they can't see any issues with her so I'm wondering whether it's my parenting 
I have a GP appointment in 2 days for DD , after I called in tears because I feel so out of my depth .
Please be brutally honest - could this be just "bad" behaviour or would you say this isn't normal ? Examples:
DD doesn't like to go out anywhere spontaneously - suggestion of soft play / park etc on a whim are all met with tantrums and refusal to go .
I often don't bother going out as its not worth the stress .
If I tell her in advance we are going to X in Y amount of days she will be happy - but sometimes when it comes to actually doing it she doesn't want to go - and tantrums.
She seems very sensitive to loud noises , low sounds and textures such as jeans - resulting in a refusal to wear certain clothes - this is a daily battle and is wearing me out.
She hates socks and underwear.
She is very emotional - usually either very upset or very angry - glimpses of joy seem very over the top , almost fake .
She has lots of friends and can be sociable but I've noticed more lately that as more children join the group to play , she quietens down - she will play but isn't loud like the others .
She is very rude / cheeky and no amount of sanctions seem to resolve it .
She lashes out - again no amount of sanctions resolve this .
She becomes very attached to things like sticks , bits of rubbish etc
She constantly ignores me when I ask her to do the most basic of things or will have a tantrum
She's very close to her cousin who comes to play a few times a week but DD has a very hard time sharing - she refuses to allow her cousin to touch her things and can lash out
She needs to have "revenge" - if her cousin accidentally hurts her , she hits her twice as hard even though we explain it was an accident , she just keeps repeating "she did it to me !"
I could go on and on but I'll try to keep it as brief as I can 
I'm at my wits end and I don't know what to do .
School say she doesn't display these behaviours there . When I ask DD why she doesn't act like this at school , she says it's because she doesn't want to lose her friends .
So could it be my parenting ?
I really need to do something as this is happening every day and I feel my patience running low .
Opinions please ?
Be brutal but gentle as I'm feeling very fragile 