How long has she been losing weight? Do you know what she weighs now?
I would be taking her for a check-up with a full senior blood panel and urinalysis as soon as possible, and get a copy of the results. Even though you take her to the vet every year, something could have come up since the last visit. Common causes of weight loss in older cats are hyperthyroidism, diabetes, kidney disease, and cancer. These are mostly manageable conditions when caught early enough. Are there any other symptoms, like excessive drinking or peeing? Eating more or less than usual?
As for the food, definitely a switch to something with better quality ingredients and more protein would be a good idea. The best thing you can do is ditch the dry completely and feed only a wet food diet. Fancy Feast isn't the worst, but there are better choices, like Wellness, Nature's Variety Instinct, Innova Evo 95%, Merrick, Eagle Pack, Precise etc. Some more info for you on what cats should be eating:
www.catinfo.org