Is it normal i'm exhausted all the time in my twenties?

it can be alot of things, from stress and over worked. To diet (food allergy and intolerance included) work out habits.

Even your bed if it isnt comfortable to you makes you restless in your sleep.

more detail would be needed to try to begin to help

Don't go to holistic doctors. Science is too important here. Go to a high powered research hospital. Keep seeing different doctors until someone knows or cares how to treat you the right way. Don't just medicate yourself or diagnose yourself. Find an expert. Not all doctors are expert. I work with, am related to, and am friends with a lot of doctors, and they usually don't know or don't care.

You sound a lot like me up until recently.
Ever since middle school I've had problems staying awake during the day, regardless of how much sleep I've had. It has affected my grades in college, which doesn't help my mental state since this makes me feel horrible. I've had trouble with memory and have generalized anxiety and depression.

I surfed the internet for possible causes, which we all know is a bad idea. I went to a number of doctors over the years for various health problems: insomnia (since childhood), headaches, GI problems, and concentration issues to name a few. I can't tell you how many times my thyroid an iron levels have been checked.
To cut this short, here is what I have discovered in the last 8 months or so:

- I have sleep apnea. I did a sleep study at a local hospital for one night and found out that I stop breathing at times during my sleep. A CPAP machine has drastically improved my energy levels during the day. SA is often associated with obesity, but that's actually not the case for most people. Mine is due to the fact that my air passage and mouth are smaller than they should be.

- I have ADHD (I suspected this in high school but waited until my last year in college to check it out; bad idea). I believe this is what has caused my anxiety and depression, which tend to make a person exhausted.

- My back was misaligned. I started to take Vyvanse for ADHD, which allowed me to sit still and study for hours at a time (which I had never been able to do). However, this started causing back pain and, eventually, neck pain. My friend suggested I see a chiropractor, as this helped her with her headaches. After a full examination we found that 8 of my vertebrae were misaligned (subluxation is the term) and putting pressure on a number of discs (C1, C2, C4, C5, T5, T8, L4, and L5 were all the ones that had, over the years, been twisted out of place). Also, my left hip was 6 mm lower than my right hip (1 mm is acceptable, but a difference greater than this causes problems with posture, walking, running, etc.).

I was told by my chiropractor that back and neck pain are usually the last symptom of subluxation, but people don't think to see a chiropractor until this point. HERE is the reason why subluxation is a problem: nerves travel through the spinal cord and exit through vertebrae to various parts of the body and are responsible for keeping our bodies functioning properly. When the spine becomes misaligned (as it does over time for everybody) nerves get pinched. For me, the nerves that exited through the vertebrae that were out of place led to specific parts of my body that were causing me trouble.

So, when a nerve gets pinched it is unable to function properly between the brain and its destination in the body. For example, when nerves that lead to the intestines are stressed/pinched you will eventually have noticeable problems (bowel movements, bloating, cramping, etc.).

Over the past few months I have received treatment to realign my spine and strengthen my back, neck, shoulder, and hip muscles (by strengthening muscles along the spine you will keep your spine in proper position). I have felt so much better recently because of this. I can finally stay awake during the day and am getting better at focusing. I plan to continue going to a chiropractor at least twice a year from now on for an adjustment. Regular adjustments will prevent excessive misalignment.

TLDR: Go to a chiropractor for a full exam, including x-rays, to determine if subluxation of your spine is causing problems elsewhere in your body.

Before you do anything, PLEASE remember to zip your trousers up. It embarrassing to forget

My first guess would be stress, depression or something else, but I am not a professional. You are the one that would know best, since the doctors didn't help, maybe you could read about different things on medical websites and then talk to a doctor if there is something you suspect it might be.