Yes, wheatgrass can be helpful. It is easiest taken as tablets of liquid extract,
It's difficult for me to give anyone a specific diet. In general, you should try to establish good dietary habits at a young age. Fresh fruit and fresh vegetables should be eaten regularly. Real food as opposed to processed foods in preferable for everyone. Avoid empty calories and junk food. Your child with always have lower than normal Hb level, so it is best to make sure food is nutritious, so the child's health can be optimized. Thal minor won't affect age of menstruation or menopause. Keep in mind that one of her parents is also thal minor. You can expect a similar level of health for your daughter.