Gee it's hard isn't it. And it does wear you down...sorry you are in this place and have had to go through all this. Like you, I also feel pretty obsessed by TTC, and I also read, do yoga, go to the gym, go for long walks with the dogs and really do my best to try and help myself, and find acceptance and find hope and positivity etc...while also letting myself be down sometimes too, to grieve. But even then, it sort of hangs over me.
I guess it's hard to define whether you are lapsing into depression... pretty easy for that to happen, given the strain of the circumstances, and sometimes 'being strong' isn't enough. Although, other times crying and having a rant is a natural resposne every now and then.

That said, I've taken anti-depressants in the past, and I would not take them personally while TTC. Perhaps talk to a psych to help ...I just wouldn't want those drugs in my body when TTC. hugs to you

p.s. I also have acupuncture and see a naturopath...he has put me on some wonderful natural remedies to help with emotional stress...so maybe that could be another natural option for you