Sadly for you
@Peng ********
you needed a MINIMUM of 15 days left on your current stamp to apply for a 90 day Non-O visa at an immigration office and it sounds like you didn't have that when you first tested positive for covid.
You also didn't go get a PCR test but went with a self test, AND decided to self isolate without going to the hospital
Without documentation from a health care provider you aren't gonna get a pass on the overstay, which means IF your stamp ran out on the 19th you're gonna start running on overstay if you don't go get an extension on it TOMORROW (if your stamp runs out on a day the immigration office is closed you are allowed to apply for an extension like normal the very next day they're open)
Unfortunately, IF you do go on overstay it means you cannot apply for an in country Non-O visa at an immigration office.
The rules state specifically that anyone who is on an overstay can't apply for in country visas 😕
Sorry you caught covid, BUT right now unless you're gonna send someone (with power of attorney and a letter from a hospital treating doctor) that you have covid and that they can get the extension on your behalf, you're gonna overstay, you're gonna not be able to get an in country Non-O visa and you're gonna hafta leave/come back and start all over with the "get the marriage visa plan"