Is this normal or am I losing my hair at 21? (Photo)

It is better to get an in-person consultation with your dermatologist to define the type of the hair loss. The Minoxidil, The PRP Treatment and vitamins can be recommended at this stage.

This needs an in-person evaluation. I suggest seeing a hair loss expert now to evaluate and go over your condition and provide you information about your best treatment options. There are great non-invasive options like prp/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

From the photos this appears to be the beginning of androgenetic alopecia (AGA), or male pattern hair loss. Given your age it is important to see a physician to consider beginning finasteride to mitigate the hair loss as it evolves over time.

The best way to find out is to see a professional. For many, hair loss is hereditary.
Dihydrotestosterone, or DHT, is a derivative of testosterone and is what
has been found to cause hair loss in both men and women. About 50% of
men and 20% of women have this defect one one of our hereditary genes
which overproduce this. As a result, high levels of DHT leads to
problems such as hair loss and balding.
However, there's also other causes of hair loss such as stress, diet, trauma, and some medications.
The number one first step I recommend is a comprehensive consultation with a hair regrowth specialist who will perform lab tests to determine the underlying cause of your thinning. Without labs, no-one can really know what your true cause is and any treatment will be temporary at best. From here, you can receive the best treatment for your case. Good luck to you and do not hesitate to reach out with more questions.

I would suggest an in-person evaluation with a Board Certified Dermatologist. Treatments could include PRP, as well as supplements or drugs like finasteride. PRP, or platelet-rich plasma, encourages the hair follicles to enter an active growth phase, causing the hair to start growing again and causes individual hair shafts to thicken. 

Hi there,It appears that you may have Alopecia.  Please see a Certified Physician to give you the proper diagnosis and treatment!  Best of luck....