It's possible that being clinically depressed is independent of trans issues and hormone levels, but said depression is still significantly affected by them.
I was good on hormones for nine months. Giddy, ecstatic, whatever-else-have-you, but upon switching to progesterone I have become severely depressed. I was taken off it after the first month, but the depression only got worse and has persisted since. It's possible the progesterone had nothing to do with it - I lost my job at the same time, more or less, and the manner in which that happened was very damaging to my person. It's also possible that they were both factors, as these last nine months have been more hellish than the usual fair.
I've been depressed for as long as I can remember, with the exception of those first nine months. I miss them, but I believe the two issues of hormones and lifelong depression are more separate than I might have previously thought.