Hi Vee,
My son had his tonsils and adenoids removed when he was eight and a half (a year ago). Both were very enlarged, causing breathing problems during eating and sleeping as well as a constantly stuffed-up nose. In the case of his adenoids, they were so enlarged that they blocked his eustacian tubes so that they could not drain completely, and his inner ears were constantly had fluid that could not drain. A cesspool of germs, an infection waiting to happen.
These were the cirumstances for which we decided to operate. His MD said that the adenoid situation was not likely to change but that he might possibly outgrow the tonsil enlargement. We decided just to have both removed because it was equally possible that the tonsils would remain enlarged, and also there were some studies that showed that in later years people needed to have tonsils removed anyway. The MD told us that the older the patient, the more painful the recovery. We said let's just do it now.
The surgery went like clockwork (his MD/surgeon was Dr. Minali Amin from Children's Hospital, Boston; she is WONDERFUL). The recovery also went exactly as expected, which is that the first week was very painful and difficult for him. The second week was much better although he still had to rest and not play at all. The recovery time is a full two weeks no matter how the patient feels.
Since having the surgery my son sleeps and eats so much better. We haven't once doubted the decision to have the surgery.
It seems like a consult is needed to determine if your daughter needs the surgery, not just on her moods, etc., but also on what's happening on the inside with the glands themselves. Good luck making your decision.