OP, my feelings about lockdown are well documented on here, and they are exactly the same as yours.
I, too, lost my job in March - a successful career which I have spent my entire adult life creating (so never mind anyone who says it's our own fault for choosing an unstable career: my career was stable. I now have no income.
Anyone who thinks "snuggling" and "hot choc" will make everything alright needs drowning in a large vat of the stuff.
The fact is, OP, this situation is infinitely worse for some people than it is for others. We are absolutely not all in this together. I can't begin to see why my children losing their home is a price worth paying for a virus which is not going to do any lasting damage to the massive majority of people who catch it.
The one thing I'm grateful for is that my children are at school and university. I haven't got a clue how I would cope if I had a baby or small children too.
OP, it is of course possible that you are suffering from PND, exacerbated by the situation, and it's always as well not to rule it out. It's equally possible, though, that your mental health is suffering "just" because of the situation. Face masks, social distancing, staying inside, not seeing friends and family (or even acquaintances at the school gates, baby groups, at work, etc, etc, etc) is not normal. Most humans thrive on being out and about, talking to people, doing things, earning a living, going to concerts/theatre/pub - whatever floats their boat. They do it, on the whole, with other people. It is monstrous to expect people to live without this for a week, never mind months on end. Not to mention how people are supposed to live with no job and no income.
It makes me feel quite sick that people can blithely talk about "seeing the GP", or "getting a prescription" - as if the answer to this completely, spectacularly miserable and shitty situation is to treat it as a medical problem which can be solved by drugging the people who are unhappy about it.
I really am with you a thousand per cent, OP.