the first thing I was going to suggest was exercise, but you have CFS, so maybe not. you could always try going for 60 minute walks 4-5 times per week, as even little bits of exercise will help raise your metabolism. I’d also strongly suggest weights, but again, if that’s too much for you, then don’t. I was stuck at the same weight for about 4 weeks, so I know how irritating it is. eventually I started cycling my calories, where I’d eat 800 calories one day and then 1600 the next, and repeat it over and over (it averages out as 1200 calories) so that my body didn’t know what to expect. you are eating too few calories at the moment, so I’d try increasing your intake at least to 1000 calories. you may gain a little weight at first, but it will help push you under 120lbs if that’s what you really want. good luck!