Sorry to hear that you have been struggling again.
I've certainly experienced similar. From my limited understanding, it's mostly biology. Your body doesn't want to run on not enough fuel and if it senses another 'famine', it will react to try to prevent that. This can happen even if you're just *thinking* about restricting, because brains are weird things we don't yet understand very well. It's not a personal failing, it's your brain and body doing what they are supposed to.
I think it's also important to emphasise that eating or not eating aren't in any way moral issues. People who eat enough are no better or worse than people who don't. Your struggles are valid either way, but as you say there are less harmful ways to cope with anxiety - do you have any access to support for your mental health? It could be worth looking on the BEAT or Mind websites, I think both offer online support or at least signposting. And there's here of course. It's very quiet these days but you will usually get a reply even if it takes a few days.