Hey, how's your fish doing?
I noticed a couple husbandry practices that I think you could use to help your fish. Even if she seems to be okay now, I think in the future it will really benefit your fish.
First, you should have a heater because bettas are tropical fish and like to be kept around 78-80 degrees Farenheit.
Second, you should always add water conditioner. Aging water for 24 hours is great, and you should keep that up, but it doesn't necessarily take out all the nasties in tap water. I believe aging tap water gets rid of some chlorine, but not chloramine, but don't quote me on that. I do know that it's still a good idea to add a good water conditioner. I prefer Stress Coat+.
Finally, I've heard that flakes aren't necessarily the best food to feed your fish. I think they've been known to soak up a lot of water in the fish and cause bloat and swim bladder issues with bettas. I think that its possible that this is why your fish looks bloated to me. Most people recommend pellets like Omega One Betta Buffet or New Life Spectrum. Frozen foods like brine shrimp or bloodworms also make for a nice treat for them.
You can try fasting her for a day or two, and if she's bloated she'll eventually poop and problem solved! If she's eggy it'll also clear up on its own.
Good luck with your fish! You seem like a very caring fish mommy.
