As you say it is very understandable that you are struggling after the untimely death of your DH. The thing about feeling low and clinical depression is a tricky one. I can only tell you my own experiences. I lost my best and closest friend to ovarian cancer (when we were both 46 as it happened) and I was off work for a month with what I thought was depression, crying bouts, only wanting to talk about her and the illness/death, would suddenly remember something we'd done together/or something funny and would start to cry (this would happen in the car sometimes and I'd have to pull over) I went back to work after a month and that was tough because we worked together too, and of course everyone wanted to know how her DH was and the 3 children she left.
I seemed to be more or less ok though still sad, but then 6 months after my friend died I had an episode of severe depression - built up very quickly - started with physical symptoms - feeling dizzy (all the time) suicidal thoughts, scared stiff of how I was feeling, long bouts of crying, just awful - never felt like that before. It got worse and I ended up in a psychiatric hospital for 3 months and on medication. I made a complete recovery and was on the meds for 15 years and no more problems.
I then started to come off the meds very gradually and 4 months after I'd come off them, I relapsed and was back in hospital for 3 months and haven't made a complete recovery this time (5 years ago) and have tried several different ADs. I'm on Sertraline 150mg at the moment with others added in. Bit I'm 71 and apparently it's harder to make a complete recovery when you're older.
SO all I can say is clinical depression is very different from "feeling low" - and usually makes you feel empty, flat, totally unmotivated, lack of interest, numb, almost an absence of any emotion. Mostly we want to withdraw from life - hide under the duvet - don't want to see people, feel scared, have suicidal thoughts and even think of ways of committing suicide. IF you have any of those symptoms I think you need to stay on the meds, but the trouble is, the only way you will know whether you need them to stay on an even keel is if you stop taking them and then go downhill. It's all trial and error with ADs I'm afraid. For some reason people don't like being on ADs but I learned the hard way and I'm sure if I'd stayed on them I wouldn't have relapsed. Anyway you can't have been on them for very long, so I think the best thing is to stay on them for the time being - especially through the winter and you are having to face a lot of "firsts" without your DH.
GPs in my experience aren't very clued up about meds or how/when to come off them - but they need to be reduced very gradually, but don't be in a rush to come off them.
Have you had any bereavement counselling - I didn't and wish I had, as I think it might have saved me from depression, but of course I'll never know about that. My friend has been dead for 21 years and I still miss her and can cry about her at times.