I understand your frustration and concern. Have you tried home cooking or anything else besides kibble and/or canned food, e.g. - raw diet?
As of recently I'm also having trouble with my girl eating. She is 6 mos old and weighs about 3.4 lbs. She was on kibble and homecooked meals (mainly steamed chicken breasts and cooked lean beef - a few times I gave her a thinly sliced NY sterloin steak (2 times) and a pieces of a fish fillet sandwich) - that's basically all she would eat. She refused anything else (veggies, fruits, etc.). Well, now it's only getting worse. She won't touch her kibble (I've even tried 4 new types, won't touch canned food - I've tried that also, and is no longer fond of the chicken or cooked lean beef). She does still like the steak (fed that to her today because she wouldn't eat), but it's not something I really want her eating all the time. At this point I'm concerned she is not getting a fully nutritionally balanced diet. Today I tried for the 1st time raw (NV Chicken) and she turned her nose up at it.
I don't know what other options I have at this point. She does come sniffing around whenever I'm eating and wants what I have or at least thinks she does - something that may be playing in to her refusing her food since I have given in a few times and hand fed her?