To me it seems as your daughter is really having two problems: one is that she is far too impatient, and want to get done with things and therefore rush through her words in order to be done with it. The second is that she is always under pressure when she writes anything at all. This means that writing is not fun, it is a task that she performs because she is asked to, and a task on top of that which she always gets wrong. Which definitely is no fun.
So, to begin with, I would concentrate on finding word/spelling games that she really can't fail to give her some confidence in her own spelling skills. For example "complete the word" games. They were really helpful in my family, when we were learning English (which is our second language).
The game is really simple. For the first task, write down words that all have the same ending on a piece of paper (this is your key). Then, write down the words with letters missing, substituting the missing letter with a line. Then read the words to your daughter and have her write them. Choose simple words to begin with like right, night, sight, light, bright, tight etc. Words with patterns to them.
Since she is a whole word reader, this "complete the word" game is very helpful to make her make the connection between pronunciation and spelling, at the same time as it allows her to practise recognising words on the paper.
Another helpful game is "jumbled words". Read through some of her writing tasks, and pick words that she usually jumbles up. Choose the ten most common, and write down her spelling on a piece of paper. Then write down the correct spelling on the reverse side. Hand her the paper before you start cooking, for example, and ask her if she can figure out how the words are supposed to be spelled before dinner. Giving her the key (telling her there is a key on the backside) will allow her to correct herself. To not be judged in case she just can't figure a word out. To correct it herself, without any pressure.
I really think the key to improving your daughter's spelling is to take away the pressure. Give her a fun workbook, that she can work on before dinner, with word games and let her have access to the key (I frequently cheated my way through my workbooks as a kid...but really that is also a way of learning, since I saw the correct spelling/grammatical form and had to fill it in to finish the task).
Though...in my case, the best thing that ever happened to me was being given my own computer, with a word processor. Unlike your daughter I loved writing (and still do), and with the help of the spell check (and a dictionary when I was convinced my spelling was right) I made very quick progress.