I've felt like that for most of last year. And that year before too, but that year I didn't saw a T or Pdoc.
Last year I tried several meds and it took more than 6 months until there was finally a med that worked a little bit. It wasn't until October/November when I finally started to feel less bad.
I'm not sure what kept me going. There were many times I wanted to quit, because there wasn't any improvement. I think I kept going to T and Pdoc because I didn't really had another choice.

Going through days when you feel that bad, so hopeless, it's really hard. I often laid on my bed crying. There wasn't really anything to make me feel better. I watched stupid television like Family Guy and Tel Sell. That helped me to calm down a bit, to take my mind of real life. Eventually I had to stop crying because it's exhausting to feel so so low.

Keep going to your T and Pdoc (if they're good). Keep trying meds. There are so many. Hopefully there's one that can help you to feel a little less bad.
I don't know much more. I've searched the internet many times to find advice on what to do when you feel so hopeless and when your sucidal ideation is so big, but everything I found wasn't helpful for me.