How to know if anti depressants are working?

A little background, I am 16 and am on Amitriptyline. When I was 11 I began to self mutilate myself by cutting and at the age of 13 I had stopped for a while. I realized I had a problem and felt severly depressed so when I was 14 I began my anti depressant journey. I started off on celexa but it just did not feel like it was working so I then got put on cymbalta which made me hallucinate and feel dizzy constantly. After the cymbalta I was put on zoloft for the longest time I have been on any anti depressant. I felt like it was working but it made me so numb, like I could not feel any of my emotions. I still cut at times very infrequently, but it still happened even while I was on the anti depressants so I figured they just were not working. This whole time I have been on any anti depressants I feel more in my head and I can't stop thinking, like I get stuck in my brain. About a month ago I had been prescribed amitriptyline and am now on 25mgs and I am supposed to raise it to 50mgs in the next week. On the amitriptyline it seems like my feelings are enhanced about 10x more than usual. This could be because I was so numb on zoloft and since I am now off of it my emotions are just rushing back, I'm not sure, but I feel my emotions so much more. I cannot tell if this is a good thing or not but i suppose it is better than being numb all the time. A lot of the time I just feel as if I am crazy and insane and nobody feels the way I do which I know is untrue but it is so hard to stop thinking that. Basically my question is how do you really know if an anti depressant is working? How are you supposed to feel? I'm beginning to wonder if I was happier without them, but I can't remember how I felt before them,but I suppose pretty crappy considering I cut myself which is not healthy behavior for somebody who is not depressed.