Nail biting is not listed as an obsessive compulsive disorder (OCD), as it does not have many of the features of OCD. Nail biting does not share many of the attributes of OCD, as it is generally pleasurable (42% of people with nail biting report pleasure after nail biting, whereas people with OCD do not find compulsions pleasurable) it rarely occurs with OCD (only 3% of people with nail biting have met criteria for OCD), and it onsets in childhood (OCD onsets in early 20's) . In fact, there was no correlation between nail biting and OCD or other anxiety disorders (Pacan et al., 2014).
So in the vast majority of people with nail biting, it is not debilitating, and it is at worst an annoying habit to reduce stress and at best a pleasurable experience. Nail biting's ego-syntonic (behaviors that are acceptable) nature is the opposite of the egodystonic (inconsistent with one's beliefs and personality) compulsions seen in OCD.
However, if nail biting is a coping mechanism for you to reduce stress, or if your nail biting is out of control and take up most of your time to the detriment of other activities, then it is time to seek help for your nail biting. You can utilize relaxation techniques to reduce the stress. You can also participate in cognitive behavioral therapy (CBT) if your nail biting is severe and no longer pleasurable. If you have a co-occurring anxiety disorder, then it needs to also be addressed. You can start by taking an anxiety test here.
Onychophagia and onychotillomania: prevalence, clinical picture and comorbidities. Pacan P, Grzesiak M, Reich A, Kantorska-Janiec M, Szepietowski JC. Acta Derm Venereol. 2014 Jan;94(1):67-71.