Why does my hair stay at the same length and doesn't grow longer no matter what I do? Same length as 5 months ago.

Hair
length has to do with how long your hair stays in growth and resting phases.
Every hair grows for a certain period of time and then it falls out fortunately,
it is followed by another hair growing from the same follicle in 4-6 weeks. The
limitation of the growth phase determines the final length of each hair. If you
are still concerned, make an appoint to see a hair transplant specialist.  It would be helpful to have a microscopic
evaluation to see if you are having miniaturization of your hair, simple
breakage or loss related to stress ie telogen effluvium or other.  A microscopic evaluation will also help to
pinpoint if you are having frontal and crown loss verses generalized thinning.

There are a few reasons why hair won't grow long.  You might be interested to learn that many individuals with hair loss claim that their hair has stopped growing and hasn't grown in many months. This is actually impossible.  Hair MUST grow because the machinery at the bottom of the skin is a living tissue. Hairs can not sit in the scalp for months and months stagnant. What is happening is either the hair is 1) breaking off, 2) coming off, or 3) not growing long anymore due to shortened growth cycles.  You might want to see a dermatologist - androgenetic alopecia, trichorrhexis nodosa, telogen effluvium and adult loose anagen syndrome need to be considered. 

Hair that does not grow usually reflects an end stage of genetic balding in that area of the scalp. Your biggest enemy is the progressive thinning leading to a balding pattern that is not evident at this point in time. The degree of thinning that you are experiencing would suggest that you should see a doctor who most likely will get Bulk Measurements of your hair to determine the degree of the thinning that you are presently having. If the diagnosis is early genetic hair loss (the most common cause of hair loss in young men), then the best treatment would be the drug finasteride which is highly effective in men of your age and may not only stop the hair loss but possibly reverse it. If you are developing a more advanced balding pattern the best test to get will determine the Bulk Measurements of your hair and this will show, over a one-year time frame, how effective the treatment will be. Once you know this information, then you and your doctor need to develop a MASTER PLAN which will define what you need to do over the years to come.