@Whyisthishappeningtous I have always erred on the side of encouraging my dd to go out and 'take part in the world' (so friends, college) perhaps at the expense of stricter calorie retention as she was depressed for a long time (I mean diagnosed, under psychiatrist). There can come a short time, which it did eventually for us, that she couldn't go out, but knowing there was a whole world of friends, events, college, and future out there is proving a good motivator for recovery.
Try not to see any day or meal or choice as right or wrong or make or break. This is a long-haul illness, and even after they are 'recovered', they will have to go and live in the world as adults perhaps still with these vulnerabilities and worries. Her going out was hugely important in terms of confidence and breaking the ED voice, the cost was fewer cals on that day. All these days pan out differently and I wouldn't worry about any individual one, just get back with the program the best you can on days she's not going out. We also compromise, my dd is driven round/taxis everywhere to minimise cal output at present, no buses or walking really, but that's due to her being hospitalized in past month, and not everyone can do that. you sound like you and her are doing better than you think.