I haven’t even been able to go to the loo alone
Come on, OP. I wasn't able to go the loo alone for about five years solid as I was at home for days on end with the children, and sometimes at the weekends too. In the end, I got so fed up with carting babies and toddlers upstairs to the loo that used the potty downstairs instead. Plus it's jolly difficult to climb stairs at toddler pace with a full bladder, a weak pelvic floor, and an armful of babies. You really are capable of more than you think you are!
Now, as you say, "the Plague" is in your house. This is where you need to erect a mental STOP sign before you start catastrophising ("Covid is here, and I'm going to die of it").
Break it down.
Covid is in your house.
What is the worst thing that can happen?
I'm going to die of it.
How likely is this?
It's 100% likely because I'm so overweight.
Is there anything that might make up for your weight?
I'm young.
I'm otherwise in reasonable health.
I'm female
I have had what appears to be the dream team of mixed vaccinations.
The overwhelming majority of overweight people who have Covid are not even hospitalised, never mind die.
The overwhelming majority of people who contract Covid at all, even if unvaccinated, have a minor illness.
And so on.
Once your family has got over this Covid hump - which you will - you then need to try again to find the root cause of the anxiety. The root cause of my phobia about norovirus (which still causes panic attacks in me) turned out to be to some extent related to the fact that I was absolutely terrified of the children being killed in a random accident, which in turn stemmed from post-natal anxiety.
You are young, and you can sort this out.