Concerned about my teenage daughter and seeking feedback or recommendations

Hi, I am seeing some unusual behavior in my daughter in recent weeks and I'm hoping to get some clarity from anyone who might have knowledge of Bipolar or any other mental health diagnosis that comes to mind...also understanding that it could be substance use and/or medically-based such as hypoglycemia. That said, my daughter is super resistant to going to the doctor and is 19 so I need to seek some direction independent of her for now.

Some new behaviors that I am seeing...
She is acting very silly...over the top silly and smiley
Teachers are reporting that she is spacey
She is not her normal self with me...has a lot of anger issues and hostility in general with me due to severe depression and trauma history and just not happy with life but has been clingy and very chatty, but scattered thought process and communication
Heavy duty fatigue...far beyond her typical
Her eyes have a glazed expression
Lots of sleeping after school/going to bed after coming home from school is very common and can last for 4 plus hours/this one has been going on for a while and she blames it on her depression.
Teachers think she is high but she has been very openly anti-drug use for years and continues to deny any use of drugs...she mostly home with me so very seldom with peers in the community.
These are most of the major changes I am seeing.
Thanks for any thoughts

Are there any indications of infection, such as fever, chills, aches? The heavy fatigue and glazed eyes are what I keyed into. She's the right age for Epstein-Barr. Note that I'm not a doctor -- not even close! Good luck!

Thanks for your thoughts SPG . She is reporting any fever, chills or aches but I really appreciate your questions and will keep them in mind. Thank U!

Americans seem to be very quick to diagnose people and assume things. I am going to be very honest here, This is absolutely appalling and could be considered bullying, accusing someone for being on drugs when they are not using is defamation of character and could affect her chances of being accepted in to university one day. No wonder the poor girl is depressed!! Jesus Christ. She has depression which is totally normal and common in teenagers, all she needs is some medication and counselling.

She needs a checkup by a good primary doctor and a good psychiatrist. Get referrals from people you trust.
From my own experience, I would not recommend a psychologist who can miss the point completely. They might draw her out, however
Depression is so common today that you are right to avoid jumping to the conclusion that this is what's bothering her.
The "silly" behavior does hint of bipolar or drug use. I would have been grateful to have gotten help decades earlier. Bipolar 2 so hard to diagnose.
I think you are a wonderful parent.