If you would rather not share, maybe investigate yourself and see if that is enough to try your goals again.
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?
I read somewhere that I might be deficient in certain things and I should check my diet. The depression could be my body telling me something is missing.
I started to reintroduce whey protein (I was avoiding dairy because cows welfare) and chicken back into my diet, then fish. I was desperate to get out of this state of mind. I can’t say for certain this was the cure but it worked for me (sadly) because it would be nice if I didn’t feel like I needed to eat meat.