Oh, poor you! You've really been through it. I hope you don't mind, but I'm going to go all practical on you.
First and foremost, have a nice bath or shower and give yourself a break. It's been a shit year.
It'll sound weird, but make sure you thoroughly blow your nose, clean around piercings and any nooks and crannies - the amount of dust we've breathed in from being in the house so much more than usual without the opportunities for going out to blow the cobwebs away does affect us. Wash your hair really well, rinse far more than usual, use conditioner and rinse well again.
Once you're all clean and pink, start off by shaving if you do that, and using a body cream or lotion that fills your skin with moisture. If you have the energy at the same time, give yourself a pedicure, dry your hair so it's smooth and sort out your fingernails so they're smooth and even and the cuticles feel smooth. Then go to bed in fresh nightclothes and get some sleep.
In the morning, you can plan to get your eyebrows shaped. It makes a huge difference to your face and mood, as you already look part 'done' before anything else has happened.
You might not like the size you are right now, but I can promise you that there are clothes in your current size. Buy some that fit you now, along with some underwear and new socks; you don't have to spend a fortune, just spend what you need to have something fresh to wear for each day. They're temporary, just tiding you over so that you are physically comfortable.
Then you can think about makeup. We've all been pretty much indoors for a year, so we're much, much paler than we've been probably since we were about 11. Look at a CC/BB in a lighter shade. Lay off the contouring, baking and heavy stuff and start again with a small palette of lighter shades matching your undertone (pink for example) with one mid, one contrasting dark, some mascara/a subtle brow colour (probably lighter if you think your makeup is too heavy now), some lighter blusher (or use the mid tone if it's a colour that is appropriate) and a couple of lip pencils/gloss in flattering shades for you.
You've now got nice hands, nice feet, eyebrows, a new load of makeup to be applied with a lighter touch to tone with your lockdown skin colour, soft skin and some new, comfortable clothes. If you need to, get your hair cut and blowdried at a salon, if not, give it some good moisturising treatments.
I think you will feel far better when you've got those things in place and then you might feel able to address weight gain/fitness/activity levels. Because you're being gentle on yourself after a bloody horrendous time, rather than beating yourself up for feeling rubbish.
On a health point, make sure you're getting your vitamin D especially, but some multivitamins will help you in general. Treat yourself to good food - buy the strawberries, get the fresh watermelon and feta, whatever it is in terms of lighter meals that make you feel good. Plenty of water. And take time in the morning to sit and stretch at the end of your bed before you go anywhere else - once you've washed your face/showered, you'll feel more awake and ready to go.
I'd also say buy yourself some new, low cost gym kit/swimming costume/towel. It feels good to be training in new things, you're less self conscious for a start. And then think about what you would do first - not launch into a huge routine multiple times a week, just what you like best - and then tell yourself you're just going to go for twenty minutes and then you can go home again. If you still hate it after twenty minutes on the rowing machine or treadmill, doing a gentle pace, you go home again - but I think you'll likely want to stay a bit longer once you're there.
Everything's harder when you've been knocked back so much for so long. You need time, daylight, fresh air, activity, good food and rest. I promise you it will begin to feel less overwhelming if you accept you've been through a lot and need to start somewhere small and build back up again.