Why doesn't diazepam/ valium work on me?

I take Sertralina and Victan every day but was given valium as an emergency medication, in case I'm super anxious and stuff. I started a new job a month ago and I went to take the valium and it did absolutely nothing. I'm wondering why? Like I thought I'd feel so much more calm but nope, not even sleepy. One time I took three (my psychiatrist said it was okay) and again I didn't feel shit. The next day I was vomiting but on the day I took them I wasn't feeling drugged or calm or anything. Why the hell didn't it do anything?

I've never been someone that takes a lot of drugs, not even pain killers, only started taking it this year because of my severe mental issues. I tried a lot of sos pills and this one was supposed to be really good or whatever but I feel nothing. Does anyone get this?