Hi Harriet - you mentioned you are struggling with weight gain and that you are at your safe weight.
I get this. I am the same, the day before my last session with my dietician I realised that I had gained 1kg. Not a fluctuation, actual weight gain.
I had a chat with him. His advice, because I menstruate regularly, eat regularly (now) and my bloods are fine, being under weight isn't an issue.
BUT, and here's the problem...recovery is about healthy thinking. One of the main reasons people relapse from this position is because ritualistic patterns emerge. They don't want to alter any ways of eating incase their weight goes up, but they are also scared for it to go too down as well. They live on the edge, and if it goes under a bit, well that's okay right? But then, going under becomes the new safe...repeat. And before you know it, you relapse.
Your weight band is there for a reason. You can trust your weight band, because it doesn't biologically force you into binges which are caused by your body wanting you to regain lost tissue. You target band is predictable with fluctuations of 1-3kg, and you are less emotionally vulnerable at that weight too.
I don't deny it's hard...I'm in the same position, because having just been discharged from outpatient services, I'm taking managing on my own as my first priority. But I wanted to reiterate that they are right, and sticking to the plan is the most important thing ever.
When I was discharged from IP care in 2007, I thought my mealplan was too much, and starting cutting out snacks and then dessert as soon as I got home. Before I knew it my lunches had become salads and then carbs went, and then I had started overexercising, and then I entered a relapse.
Stick to the plan. 