First, if you are not seeing her overgrooming, then her lapse in coat quality is likely a combination of poor nutrition for the skin/coat (since weight loss cats often reroute nutrition for these non-critical organs to more important ones) and could also be in part to stress induced overgrooming. And I would note that any internal issue that could cause a cat with a good appetite to have weight loss could cause physiological stress for a cat. So, these signs are likely a side effect of a bigger issue.
Now focusing on Midge's weight loss, as I am sure you can appreciate, we do have to be wary of a few issues at her age. When considering triggers for weight loss, we do tend to consider 3 categories of causes. Specifically, her weight loss could be related to:
(1) decreased nutritional input (less of a worry if she is eating normally);
(2) increased output (less likely if she has no signs of diarrhea or increased urination but still a potential issue if her urine has more protein then it should), and
(3) due to an internal process that is siphoning nutrition (this is where issues like metabolic diseases like diabetes, hyperthyroidism, organ troubles, or cancer lie. Worms would also be in the group, but less likely if you have used a roundworm wormer as well).
With this all in mind and because those third category concerns are at the top of our list here, it'd be ideal to have her checked by her vet at this stage. If she is due a booster soon, you could consider moving up that appointment so that she can be checked. If their examination can rule out any sinister masses, then you may want to consider having her vet check a blood sample to rule out and pinpoint the other concerns in that group of conditions.
Otherwise, if you want to hold off having her seen at this stage, you could alternatively collect a urine sample and submit it to your vet to analyze. Often we can obtain a ‘donation’ if Midge is left overnight in a non-carpeted room with an empty litter box. The vet will be able to analyze it and determine if there is anything abnormal. They will be able to appreciate changes to the urine's white blood cell content (a marker of infection, which is good to rule out since it is so commonly seen secondary to diabetes), bilirubin (a marker of liver disease), specific gravity (to tell is the urine is as concentrated as it should be and a hint of kidney troubles), protein (to see if this is where our weight loss is going), and the presence of glucose/ketones (markers of diabetes). So, this can be an inexpensive and non-invasive way of starting to rule out some of our concerns for her.
Finally, I do want to touch on some supportive care that you can consider. Since her current food intake is just not helping her maintain her weight, you can consider offering a calorically dense diet. Examples of this are Hill's A/D, Royal Canin Recovery, or Clinicare Canine/Feline Liquid Diet. All are very nutrient rich, so a little goes a long weigh and can get more into her. In the same vein, you can even offer kitten wet food. This too will have more fat/calories/nutrition per bite then her regular food and can just get more nutrition in to better balance those current losses.
Overall, these would be our concerns at this stage for your lass. You have done right so far, but if we are still losing weight despite appearing normal, then it'd be best to consider having a check up with her vet +/- having blood (or urine) sample taken to start narrowing down triggers for her signs. Because once we pinpoint that cause, it is more likely that we can address it and help her get some weight back onto her.
I hope this information is helpful.
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All the best,
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