How long will it take to show the effect of Desvenlafaxine?

Hi doctor,

I am a 42 years old male. I had low mood with anxiety problem around two years back. I was on Desvenlafaxine 50 mg ER tablet prescribed by GP. I took it for around eight months and felt better. Then I consulted my psychiatrist and told that I have only anxiety. So, he prescribed Clonazepam 1 mg and Alprazolam 0.5 mg in the morning and Nitrazepam 10 mg and Clonazepam 1 mg in the night and stopped Desvenlafaxine 50 mg ER tablet. I slowly tapered from first month itself to finally in around one year; I was on 0.25 mg Clonazepam in the morning and 2.5 mg Nitrazepam in the night, which I felt has same effect as I started. Later, I tried to come out of it without any medication, but I was feeling anxious. Actually, I felt better with Desvenlafaxine 50 mg ER tablet, compared to other anti-anxiety medicines. So, I asked my psychiatrist and he said start taking Desvenlafaxine 50 mg ER tablet. But, I do not have the same effect as I felt earlier. Now, it is almost seven weeks. I am taking 2.5 mg Nitrazepam in the night and occasionally, Clonazepam 0.5 mg or Alprazolam 0.25 mg or 0.50 mg when I feel more anxious. So, I want to be only on Desvenlafaxine 50 mg ER tablet as earlier. Should I wait for some more time? Or should I increase dose to 75 mg or 100 mg? I really appreciate your help. By the way, I feel more anxious only at traffic signal or sometimes waiting in line at grocery store or sometime anticipatory fear in going far from my home. Thank you very much for your help.