Hello Mark. Peace has given you a pretty good answer. I'll try and add a little. My experience has been that everyone is different, but sometimes docs try and treat us all the same. It's been my experience that each doc has several medications that they prescribe first. That is fine as long as they are willing to change them up when they don't work. I would have gotten a lot better , a lot sooner if I had made my docs change my meds quicker when I was really ill. If a medication is going to work for you, you will generally show a large improvement in how you feel within 60-90 days from the time you reach maximum dose. I don't know how many times I went 6mths or even more than a yr(s) with a medication that only slightly improved my moods.
Basically if I wasn't suicidal my doc didn't want to change my meds. That can still leave a person feeling pretty low. In order to get better I had to try many different meds in a variety combos and I went with the "if I don't feel vastly better in 90 days I want something different " attitude and that helped a lot.
Of course I had to do some difficult things myself , like life style(exercise , sleep habits, etc) and diet changes (less booze, less sugars and chips etc) in order to make it all work, but changing my meds helped considerably.
Which ones to take? Unfortunately everyone is different, so what works for one won`t work for another, however it may help to try different classes of medication. For example Sertraline is classed as a SSRI, so maybe an NDRI (wellbutrin) may work for you. Each class of medications anti depressants works in a slightly different manner. That doesn`t mean that another SSRI may not help you (such as cipralex). Wikipedia has a not bad primer on various classes of antidepressants
https://en.wikipedia.org/wiki/Antidepressant . It certainly is not the last word in antidepressants, but it may help. Take Care. paul m