Please can anyone offer me an insight into my DD's behaviour and some advice as to the best way to parent her, because to be quite honest, I am rapidly losing the will to carry on.
I'm not sure what the alternatives are, apart from to keep plodding along, but I'm not really getting anywhere, or at least, that's how it feels to me.
I have decided that the best thing is to be completely honest here, so I hope I don't get too much of a flaming.
DD is 4 and a half.
Most of the time, dd is lovely, she is chatty and funny and bright, but whenever she cannot get her own way, she throws the mother of all tantrums. She is very defiant and destructive and will hit, spit or scream at me. She will deliberately break/smash things too if at all possible. I do tell dd this is not acceptable in a firm voice and then where I am able to, I ignore. dd is not bothered if i ignore her, when she is naughty, she doesn't respond to any discipline whatsoever, nothing bothers her. No matter what priviledges I remove, she continues the bad behaviour. No matter how firmly I speak to her, she continues dribbling spit and screaming.
Short of physically picking dd up and moving her to a safe place, there is not much else that I haven't tried to discipline dd or to get control over the situation that has worked.
I can't adequately explain how defiant dd is.
As a baby, dd was fine, ate well, slept well, seemed perfectly fine, but once she was old enough to pull herself up to a kneeling position in her cot, she began headbanging. The headbanging was ferocious and continuous. I contacted my HV who advised me to ignore, said it was all attention seeking, and I was to ignore at all costs.
I tried this, but to be honest, the constant thud thud thud was beginning to annoy me, so I tried distracting dd. This was not effective for more than a few minutes at most but I continued distracting for years just to make the bloody noise stop. I live in quite a new house and the soundproofing is not good, which means that if dd headbangs over the other side of the house to me, it sounds like someone is hammering a nail into a wall. It has been like living with permanent DIY going on, day in and day out for years.
If I removed dd from the cot to stop her headbanging, she would headbang on any hard surface she could find.
Over the years, I have repeatedly sought advice from the HV, the GP, and have seen a consultant paediatrician. All of the advice was to ignore.
dd would headbang when she was tired or feeling any negative emotion. She would headbang on concrete floors, walls, cot bars, backs of chairs, doors, the back of her car seat whilst in the car and anywhere else she could. It is so violent that my car bounces around and I can feel it when I am driving. 
My next door neighbours attempted to have me evicted on the grounds of noise nuisance and things are very strained between us even now.
Despite the advice to ignore, that dd would outgrow it, I tried distracting, or removing whenever she was doing it.
It took until dd was 4 before it has improved, and it doesn't happen much now.
Only now, it has been replaced with rocking and chanting. When I say chanting, I mean at the top of her voice. Usually when dd is tired or experiencing negative emotions.
dd rocks herself to self soothe I think, only it has torn apart my sofa, from grabbing hold of the edge and rocking back and forwards ferociously for months on end, every day, multiple times a day whilst rubbing her hair against the sofa, and chanting loudly.
Whenever dd begins rocking and chanting, I can feel my blood pressure rising!! I really really can't abide the sound, so usually cannot ignore for very long, as well as the sound of my sofa creaking and groaning with the force.
dd rocks in bed at night to go to sleep, and has a bald patch on her head from all of the head rubbing.
She also kneels facing backwards on my dining chairs and rocks back and forth, causing the legs to continuously bang onto the hard floor, and it is very loud. I can hear it at the end of my garden.
Nothing stops her. I don't want the noise of her doing it. I don't want my furniture broken to satisfy her incessant need to rock and bang.
My intense hatred of the rocking and banging effects the way I discipline dd. I have got to the point where I will do almost anything to make her stop, although I realise that is foolish.
When dd is naughty, I cannot give her a time out because she will start headbanging.
I cannot sit her on a dining chair for timeout because she will rock and bang the legs of the chair.
I usually remove toys, tv or something else she values to discipline her, and speak to her firmly. It has no effect.
I have tried seeking help for so many years and have asked for so much help, but I am only ever told to ignore the bad behaviour, use positive reinforcement and time outs. I cannot use timeouts because of the resulting banging. No one seemed to take me seriously, until dd started school. Now she has started school, at last someone else can see how defiant and uncontrollable dd can be, not all of the time I must say, but when she is annoyed/angry, which is obviously quite often.
She has bitten other children, and the school are concerned about dd's erratic mood swings. They say her behaviour can be extreme, that she kicks, punches, slaps and bites and can be unpredictable. She can be very defiant, using adult language in context aggressively. (no examples here)
School say she headbangs and kicks out, her moods are difficult to read and her responses are inconsistent.
School say her behaviour has improved slightly since starting school, and when her mood is 'read' correctly, they make progress but on some days, no approach works. Confrontation causes defiance.
I have been living with these behaviours for years, and have asked for help so many times that I am convinced no one knows what to do for dd, so they advise me to ignore, which clearly isn't getting control of the situation.
I have completely lost hope that someone somewhere can help dd, and help me to parent her effectively.
If you have any idea what I can do to help dd, without creating WW3 with my neighbours, or without having to listen to the same chant over and over for hours and hours and hours, or the incessant banging, please tell me.
I wonder if there is an underlying cause to dd's behaviour, or whether it is just shit parenting on my behalf. I have cut out all unnatural foods and drinks from her diet, it has made no difference to her behaviour.
I am dreading this half term holiday.
I am a single parent with no support from exp and very little support from family. I am now worried I am going to lose the few friends I have because of dd's behaviour. I'm sure they secretly blame my inadequate parenting. I tend not to take dd to friend's houses over the holidays because dd can be unpredictable and aggressive.
It seems that no matter what I ask dd to do, she always always does the opposite. Always!!
Sorry for the long post, but thank you for getting this far.