Wellbutrin helped me back away from the brink of suicide. It enabled me to start seeking therapy and making use of it, but like you it wasn't enough. I'd say HRT, coupled with acceptance of who I am and making the decision to transition, is what finally allowed me to master it.
I couldn't call it a panacea. That's mostly because I look at depression the way some look at alcoholism: it'll always be with you; you can't cure it as much as control it.
These days, I do get these depressive episodes every once in awhile, but they're all centered around my fears of a "successful" transition. Lately, they've been quite bad, but that's mostly because my mind is aching for me to move up to being consistently part-time. Still, I feel like I can work through them and come out the other side better than I was. They're worlds better than the months-long suicidal torpors I knew before.
Right now, I'm taking both anti-depressants and HRT. When I'm in a better place, I'm gonna see how I do with the HRT alone.