Yeah I'm confused with the wellness feeding instructions. According to them, a 14 pound cat should get three 5.5 ounce cans, but now I'm hearing it should only be one 5.5 ounce can?
Ignore the feeding instructions
Generally, you don't feed by the size of the can. You feed by calories. Two different brands of the same size and similar variety can have very different calorie amounts. Brand X chicken dinner might have 175 calories while Brand ABC chicken dinner has 125 calories. A general rule of thumb is to feed 20 to 25 calories per pound of body weight daily. A 10 lb cat might need 200 to 250 calories daily but every cat is different. Adjust calorie intake if the cat is gaining or losing weight. One 5.5 oz isn't enough for most adult cats daily so you'll need to add in part of another can. If you feed 3 oz cans or those pouched / tray foods, you may need to feed 3 or 4 or more of those daily.
Buying cans in cases instead of individually can be more cost effective. Some brands are available in 13 oz can sizes which you can split up into portion sizes and freezer if needed. Buy during those giant pet food sales Petco and Petsmart often have.