Now I have to say that I am quite concerned about Fancy.
Elderly cats with vomiting as well as increased thirst and weight loss raise some serious concerns. Specifically, we'd have to be worried about kidney issues, liver disease, or even metabolic issues like diabetes or hyperthyroidism. As well, with her age, we'd also have to consider GI tumors (ie stomach, intestine, etc).
Now I appreciate that finances and your situation limits what you can do for Fancy. Still, we cannot ignore these concerns. Therefore, it'd be ideal to see if your local vet will do a home visit for you or consider contacting your local mobile vet to come to Fancy. Or if you can get transportation or a friend to take Fancy to the vet for you, I do want to note that you could take advantage of the free first consult offers from VCA or Banfield to get her seen (which would offset the costs and make it possible to obtain antibiotics to treat this). The vouchers for these can be found at: VCA (http://www.vcahospitals.com/main/offer) + Banfield (http://www.banfield.com/landing-pages/coupon). Alternatively, you can check the ASPCA database @ (https://www.aspca.org/about-us/faq/financial-help-my-vet-bills) or the Humane society @(http://www.humanesociety.org/animals/resources/tips/trouble_affording_pet.html) as they can help keep costs down for getting her care.
Otherwise, I do want to note some supportive care that can at least reduce her nausea and slow her weight loss. This isn't a cure (since we'd need to diagnose which of those concerns were present for her and that would require an examination +/- bloods) but it could help her at least be comfortable. In regards ***** ***** you can try to reduce her nausea by treating with an antacid like Pepcid (More Info/Dose @http://www.petplace.com/article/drug-library/library/over-the-counter/famotidine-pepcid) or Tagamet (More Info/Dose Here @http://www.petplace.com/article/drug-library/library/over-the-counter/cimetidine-hcl-tagamet).
As well, since she is losing weight despite eating, I would note that it'd be ideal to 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. 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 this can just ensure we are getting enough nutrition in to balance those current losses.
Overall, I am quite concerned about Fancy. I feel that we may have one of the above issues here and that really warrants having a blood test and exam to determine which is present. Because once we determine which is causing her trouble, we can start treatment to reduce the effects of this for her and stop her vomiting and weight loss. So, it'd really be ideal to look into those low cost options or consider having a home visit for her. And hopefully if we use the above supportive care we can at least keep her comfortable until we can have her seen and start treating the issue at hand.
Please take care,