The combination of gas and voracious eating sounds like your cat may have worms. I am also unsure why she's not going to the vet until 7 mths? Is that her next scheduled visit? Has she had all her boosters, then? It's ok to take her in earlier for a checkup to get a fecal sample, or just to get the pills for parasites.
If it turns out not to be worms, there are many other causes for gas.
- She may not be tolerating the food well, even though you're giving her good food.
- If you have changed foods recently, it may have upset her tummy, and will take some time to get adjusted.
- If she's eating too fast, she will gulp a lot of air. You know the rest.
Those are some of the more common causes. There are others, but if your vet ends up ruling all of those out, you will have a gassy kitty for just a while longer. One of mine was gassy with no obvious cause, and grew out of it a year later. Another gets gas when she sneaks food from the others' bowls, and the adult food is too much for her.