I went through this 2 cats ago and it turned into diabetes, which is no picnic. I was ignorant as to what to feed her and the foods available weren’t as balanced back then. For mine it was too late (much older than yours by the time I figured it out), but I took her to the vet, and they re-educated me and gave me tips on how to get the weight off and how to take care of future cats. My cat was nearly over 12 years old at that point and I wish I’d known about the problem at the point you are thinking about it.
Like others have said, you need a vet check up and some professional advice. What you need is a weight range that is healthy for your particular cat. Then, if the vet deems your cat overweight, they should give you feeding advice. Again, it should be gradual, if you have to change foods, as mentioned above. What they had me do, was to measure and observe what she ate for a week and then reduce that amount by a given amount.
Cats are either nibblers and know when to stop or gorgers and don’t. They suggested I feed twice daily a set amount, as to distribute it evenly. They said quality dry food was okay, but when a cat gets older, that can turn into a problem with chewing when the teeth start to go. Dry food is better for long term health of the teeth, but they need plenty of water.
With my new kitten, I use a blend of EVO, Science Diet and Solid Gold Katz-N-Flocken. They are carried at Bay Area “Biggie” pet stores, but I can’t buy all 3 of them at the same store. I buy the smallest bags of each, in case she pushes the reject button on one of them. They are pricer, but I figure worth it in contrast to later vet bills
The Katz-N-Floken makes her coat amazingly shiny. I want to warn you that you may have to put up with back talk until your kitty gets used to the idea of limiting her food.
The other tips you have gotten (same for humans) is to exercise her more. The lazer pointer is great, but keep it away from her eyes. We use those feather wands, but each cat likes something different. My other 2 could be leased and taken for a walk, but the new baby doesn’t seem to go for that idea, but, as I said in an earlier post, she flies and swims, so that more than makes up for it.