Ok, I've googled the bottle. Is it the one where you get a syringe that has the weight printed on it so you draw up the meloxicam to the wieght of your pet?
It looks like the initial dose is twice the maintenance dose. Did they tell you to give 2 syringes for the first dose? If not, that's probably because she already had a higher dose at the vets.
I'm assuming you only gave Molly the maintenance dose (1 syringe). The maintenance dose would be 1.4 mg of meloxicam for a 14 kg dog. The initial dose (ie higher but but still safe) for a 2.2 kg cat would be 0.44 mg so one third of Molly's prescription. So I'm guessing Jessy should be okay if she ate less than a third.
I think the main risk to Jessy would be if she has taken an overdose but it doesn't sound like she has? She doesn't have known chronic kidney disease, does she? Long term use of meloxicam by cats seems to be linked with renal failure too but she has only had one dose.
Like I said, meloxicam is still sometimes prescribed for cats despite the risk. If you look at a packet of ibuprofen (similar drug) it lists kidney failure as a possible side effect...
Maybe post on the litter tray board instead of pets, I think there is a vet who posts there. As I say, I'm not a vet, but I would guess signs of acute kidney failure would be similar to humans 😂Take her back to the vet if there is anything different eg she is listless, not eating, drinking more than usual, weeing more than usual, has vomiting or diarrhoea, cloudy wee, seems confused, is dehydrated, anything unusual...Drinking and weeing more, and dehydration aren't so obvious so maybe keep an eye out for them. To check for dehydration, check that her gums aren't dry. You can also gently pinch and pull back the skin on her neck (the scruff), it should spring back. Practice with the loose skin on the back of your hand to see what I mean!