IMO, HRT is all about how you want to age. Whether or not you take the HRT, you're going to be a different person in 5 years. Which hormone do you want to be the dominant hormone in that time? Do you want to age in a more "feminine" or "masculine" way? No matter what, time moves forward and you will be older. Are you able to imagine yourself in 10 years? I found it much easier to do so when I started imagining myself as trans.

but I don't really know if I should start because of my depression makes me unable to feel excitement or happiness at the prospect of HRT

One thing I kinda regret is that I started HRT hoping it would entirely take care of my depression that I had for most of my life. It helped, but the fact it didn't "cure" me in 6 months created a mini crisis. In hindsight, I should have started therapy and antidepressants at the same time as the HRT ( which is what the informed consent clinic recommended, but