Her last-second answer changing on the tests sounds very much like my difficult child 1, who also has anxiety and depression and therefore is getting a generic "mood disorder not otherwise specified" label on our most recent psychiatrist superbill.
That said, the answer to your question about whether one can have anxiety and depression and not realize it is a resounding YES. Perhaps if you explain it this way: it's like being a frog that's put into a pot of water, and the heat is very gradually increased. The frog acclimates to the temperature change up to a point before it succumbs to the heat. On the other hand, if you suddenly immerse a frog into a boiling pot of water, it's going to immediately try to get out of that pot. The difference between the two is that the former situation builds so gradually you don't realize you're in trouble until things are REALLY bad.
I, too, have anxiety that has morphed over time into depression when left untreated. Once I started medications, it was like a veil had been lifted and I remember telling someone that I never realized just how badly I was feeling until I started to feel good again, thanks largely to the medications ( I had therapy too, but without the two together, my recovery would not have been as quick).
Another though for your daughter is that medications might be just a temporary support if she'd be willing to go to therapy/counseling to learn better self-awareness and coping skills. Things will only get more stressful in college, and this would be a really great way to prepare her for those demands.
