I wasn't eating red meat for a while, I stayed with chicken and fish, which I don't believe are great sources of iron, then I started to feel better. I got back into red meat later on, maybe 6 months later.
I think I was eating a balanced diet, but not good enough. I did try vegetarian again for a few years at a later stage. This time, I was working from home and cooking a LOT of curries with legumes etc, I seemed to feel good and I was monitoring my mental health closely. I made sure to do a bit more protein. I would've just ate meat again if I didn't feel well but I never ended up depressed like before. The experiment ended however when I moved to another country where it was just too hard to cook and prepare vegetarian again, so I don't have much more to add unfortunately.
Maybe eating vegetarian is ok if one has a lot of time for it?
If you would rather not share, maybe investigate yourself and see if that is enough to try your goals again.