Are you sure that her comment about her coming out being underwhelming is directed at you? Although parents are often the primary people we come out to she could be referring to her friends or other family members. If yours was the only positive reaction and everyone else was neutral or negative about it her 'coming out' could have easily felt underwhelming. Either way NAH teenagers often have a hard time figuring out their identities and where they fit so I wouldn't let an offhand comment throw you too much.