Hi Katie,
It is awful to feel out of control, and eating unhealthily.
There will be a reason though. I hope you can work it out. It could be anything from childhood misery being triggered by Christmas, to all the sugar sending wrong messages to you brain.
Have faith that your body is doing the best it can, and that you will find out how to look after yourself properly.

It might help to write down a list of all the things you think might help. With food, and other health areas like sleep, exercise, socialising etc.
And then go through them and try to make realistic decisions about what might really work. Be sensible and kind to yourself. And then see if you can put them in place.

If you have had several months of feeling unfocussed, be kind and give yourself several months to get back on track. Slow and steady wins the race.

If you decide that getting successful fast days is a priority, then start planning for those dreadful late afternoons. I can get through by telling myself I can eat what I want tomorrow, but sometimes it is still very hard.
Some people find what they eat and when they eat, makes a difference: eg I only have drinks til the afternoon, then have miso soup with chicken and greens, and then I can count the hours until I have my bowl of good nourishing soup at 5pm, or later if I can hold out. Then I just need to last until bedtime with more drinks.

Maybe you can schedule some things to do in the late afternoon: see a movie, have a bath, do some yoga, cook for the next day (I have done this and it was ok!) or come on to the forums and see if there is anyone here to chat to. If you fit into my time zone, I would be glad to chat.

The awful cravings often come in waves, so if you can ride it out it goes away (for a while 😉 )

Keep working on it, and you will get there!