@Ai***
As people have stated (repeatedly :P)
On the visa you came in your first 90 day report is due 90 days after you stamped IN to the country.
SO if you stamped in on Jan 11 your 90 day report is due Saturday April 10th.
You can report in person from 15 days before up until 7 days after the due date without a penalty.
NOW let's address the fact you don't have a TM6 departure card (which you NEED to have to file a 90 day report).
I'd swing past the main immigration office near the airport OR the one at Promenada Mall and ask how to get a new TM6 departure card.
Some offices make you get a police report saying you lost it before they will replace it for you, but some don't, and that's why I said swing by before you need to do your 90 day report and ask how it's handled there.
Also when you go to do a 90 day report in Chiang Mai they have a drive thru lane for 90 day reporting at the main immigration office near the airport.
Good luck, take care, stay safe