Proper suggestion. After 3 weeks common?

I have written here a number of times about the anxiety, fear and depression that I'm going through for about a month now.. haven't got any convincing answers.. started on Nov 7th with 20mg prodep and 0.25mg petril. Since I wasn't doing good.. consulted my psychiatrist and he has put me on 40mg prodep in the morning, 0.25mg petril one in the morning, one in the noon and one in the night. And also he has added half of 7.5mg of mirtaz in the night.. sometimes I feel low, sometimes ok, it is so difficult to fight this negative thoughts and depression.. everyday is a struggle.. I have had this issue 2 years ago too.. To the genuine doctors out there, it's not that I don't trust the medicines, I want to know is feeling low even after 3 weeks common? And when will the anxiety fear and depression go away and I feel fine.. I need help and some positivity..