Judge I hope she's doing ok. Keep an eye on her, she could have a foreign body way up high in her nose where you can't see it. Grass seeds are little buggers, and can be so far up a nose or in an ear you can't see them without vet instruments.
You can try satin balls. My salukis don't like them. If her worming and all is up to date it probably is just the lactating. Is she still making much milk?
The best way to add weight is to feed her normal rations, and add extra bits. That way you know she's still getting what she needs. With my salukis when they need weight I've found cheap sausages boiled and cut up are a good extra, or one of the better quality dog rolls.