Leaving aside the issue of whether you're depressed or not, you've got a lot going on. Is it possible to drop any of these things, either temporarily or permanently?
Do you have to be taking professional qualifications right now, while you're ill with underactive thyroid, your dad's dying and you're supporting your mum? Have you told work everything that's going on in your personal life? If you haven't, I think you should.
You're supporting your mum about your dad's illness but who's supporting you? Can you afford a counsellor, if the answer is "nobody"? Do you need counselling because of the miscarriages too?
Is t possible to put the house build in hold for now and pick it up again later? If not, have you told your husband everything that's going on and how you're feeling and struggling? Can he pick up some of this from afar, like phone calls and emails and liasing with people, t take some of the pressure off you?
To get well, you need to focus on and prioritize your health. You can't do that if you're prioritizing all this other stuff.
For the very first thing, can you go see GP, basically tell/show them your first post here and get signed off work for a few weeks? You need a chance to have a rest, a chance for the thyroid meds to start working, then give yourself a kick up the bum regards basic personal care, then put some measures in place to take some of these pressures off you, so you can return to work without falling apart. You're a human being not a robot.
People don't always fall apart mentally sometimes they fall apart physically. I would take the thyroid problems and potential depression as a warning sign that life needs to change so you're looking after yourself better. Sounds like all the loads you've been carrying recently have finally become too much. The proverbial "straw that broke the camel's back". Hope you feel better soon.