Based on what you wrote you were prescribed antidepressants for severe anxiety and even suicidal ideation but other symptoms are not mentioned...First we need clarity in your diagnosis
About medicines
Nexito is not a sufficient dose, You were unable to tolerate serta.Now from 6 days you are on mirtazepine..
Generally for most symptoms 3 weeks of antidepressants at adequate doses need to be taken..Now your taking mirtazepine at 7.5mg is not an adequate dose atleast 15mg is required.
Next Steps
clarify diagnosis with your psychiatrist and target symptoms of medicines
If all this is due to personality disorder or stressor course will be different
Health Tips
speak to your psychiatrist and clarify doses.Address your immediate stressors.Might be a good idea to discuss your diagnosis,course,target symptoms of therapy, medicines with your psychiatrist and psychologist