Your nurse is wrong. A low-carb diet should get your BG back into normal range fairly quickly. That's important if you want to avoid further rises, unpleasant symptoms, and possible long-term damage.
If your last A1c was 54, it's evidence that your system cannot manage the level of carbohydrate intake you currently have, but it is probable/possible that it could manage a reduced level. We each react differently to various catbohydrates and the only way to find out what is most problematic is to test. That gives you direct knowledge of how you react to your food and therefore the information needed to cut out the things you really can't cope with.
For example - I react badly to cereals - they will spike my BG. I can eat chickpeas and kidney beans without much of an impact, however. I found this out by testing. So - I don't have bread, or porridge, or pastry, but I can have a chilli with beans and curries with chickpeas.
Unfortunately the advice the NHS insists on giving to T2s is to eat carbohydrates. This is backed up by the media parroting about what's "healthy" and what's not. Unfortunately, if you're T2 diabetic as we are, this "healthy advice" is rubbish and positively dangerous. I got to be diabetic thanks to following that pattern - I never ate a lot of sugar but ate lots of bread, pasta, rice, starchy vegetables etc in the mistaken belief they were good for me.