One test of psychosis is 'loss of reality testing'. You say that you know that people aren't trying to hurt you, it is just that you feel like they are. That sounds like your reality testing is intact.

Another test of psychosis is something that you alluded to. Jaspers 'ununderstandability' criterion. The idea here is that delusion-like ideas (Jaspers teminology) arise in an understandable way from the persons experiences (e.g., your paranoia arises understandably from your experience of bullying and abuse). Delusions proper, however (Jaspers terminology again) arise in a way that they are not understandable (they are 'un-understandable) in light of the persons history. The un-understandability could arise from bizzareness of content (e.g., 'My brain is a nuclear power plant') or the un-understandability could arise out of the blue where there is no anomalous (bizzare, strange) experience that preceeds the development of the delusion.

The understandable / un-understandable distinction is controversial. Some say that it makes whether a person is delusional or not more a matter of how things are with the clinician than with the patient. By making the clinicians ability or inability to empathise part of what makes a person delusional things seem to have more to do with the clinicians limitations than something that is going on with the patient.

It isn't uncommon for people to have transient (passing) psychotic episodes when they are under extreme stress. Trauma can be something that triggers psychotic or psychotic-like experiences. A war vet, for example, might be triggered into thinking he is in the warzone when he hears a car backfire. He might say that he can literally hear the panicked voices and other gunshots and he can literally smell the gunpowder. Such experiences tend to be transatory, however.

Can you see a therapist to talk about your traumatic experiences? Typically the treatment for post traumatic stress involves talking about the experiences. Processing some of the stuff so that one gains some feelings of mastery and control over it so that one is better able to live in the present rather than being haunted by the past.