Chi's are really hard to house train. You may find that she goes right back to peeing on the carpet when you take the diaper off. The key is supervision. You may have to have her on leash and tied to you 24/7 but they need to have all accidents prevented. That way you can also catch her when she does have an accident and correct it, otherwise if you just find an accident, you can't correct her for it.
Also make sure you are rewarding going potty outside. So go outside with her, and as soon as she goes, make a fuss over her and immediately give a treat. It doesn't work to just stand at the door and do it (then you're just rewarding coming inside) you actually need the treat to be in her mouth within 2-3 seconds of her peeing.
The diapers are fine for now, letting her get a little older will help with potty training too. But you shouldn't need them more than a few months. She probably won't actually pee in them, so you could use a cloth diaper (that would be more environmentally friendly).