Weight loss advice please

Hi, I need some advice please .

I have been ill with a long term illness for 9 years now, I'm currently on high dose pain meds . I've dropped from a size 24 to 16 but I've been stuck at my current weight for the past year now. I've no appetite and normally only eat one meal a day just due to not being hungry. I'm very active and have horses and dogs so I get out and exercise daily.

Has anyone any suggestions as to what to do? I'm worried that my Weight is Creeping back on . Thanks in advance x