This is a difficult question to answer. Many people describe having an “inner voice” that they hear on a regular basis. It is quite normal. On the basis of a short letter, it is difficult to distinguish that inner voice from the voices associated with psychosis.
Individuals with schizophrenia (or other psychotic disorders) who hear voices often describe them as being external. In other words, the voices they hear are not their own. They seem to be the voices of others. They also tend to be derogatory in nature. The voices you hear are sometimes derogatory and critical. The latter would be consistent with the types of voices heard by individuals with schizophrenia or other psychotic disorders.
Having said that, you are presently being treated for depression and other symptoms. Anxiety commonly occurs with depression and OCD. Low self-esteem is also related to depression, anxiety and OCD. The derogatory nature of the voices could be related to depression, anxiety or OCD.
Having family members with serious mental illness can increase the likelihood of your also developing one but generally speaking the risk is slight. Whether or not you will develop a mental illness can depend on many factors, such as biology, drug use, traumatic experiences, environmental conditions, and so forth.
In summary, it is possible that the voices you hear are a sign of schizophrenia or other psychotic illnesses. Your treating professionals (who are familiar with your case) do not think so. They do not believe that you are developing a psychotic disorder and I find this to be good news.
I would encourage you to read more about the experiences of individuals with anxiety, OCD, depression, and psychotic disorders. It might help to answer your remaining questions. I hope this helps. Please take care.