It strikes me that you're simply more comfortable thinking in English.

Which begs the question: why is it so that my native language that I spoke since I was two and everyone in my circle understands, is less comfortable for me than a foreign language I am not even confident in my skill with, possess a limited vocabulary (compared to Russian), and have much less practice in?

It seems like half your complaints are that Russian doesn't make some distinction that English does and the other half are that Russian forces you to make distinctions that English doesn't

Not being able to make a distinction and forcing you to make a distinction, are both bad. Look at the "It isn't a fish" example. In English you can distinguish between "It isn't a fish" and "It isn't a mammal", or you can leave it ambiguous ("It isn't"). If you can make a distinction, but don't have to, it gives you a lot more flexibility than both "not able to" and "can and must". Russian is inflexible exactly because of that.

I think Russian is just worse at carving reality at its joints. Accuracy and precision and two very different things, down to the point that more precision = less accuracy and vice-versa. That's a good distinction. Forcing you to specify a noun's gender when you're talking about it, with said genders distributed mostly randomly/historically (dare you to say why "mechanism" is male, "machine" is female, and "device" is neuter?), makes no sense, because different-gendered items do not have different behaviour. That's a bad distinction.