As long as you have a 1 gallon or smaller container for your betta, yes, you need to do changes as often as you can. 1 or 2 50% changes then a full change in one week. Ammonia will build up quickly in such a small container.
For food, I feed all mine 2-3 pellets twice a day, but if varies from person to person.
I had forgotten, but you said you fed her freeze dried bloodworms? The pellets are best, but for a treat, go for frozen bloodworms. You can thaw them out and feed them to your betta. It's better for her, easier to eat and won't give her bloat, like freeze dried might.