Help Signing up for Healthcare.gov as an Independent Contractor with December Bonuses?

Full disclosure, I also asked the tutor.com community on Reddit, but I suspect this might be the more appropriate place to ask.

I’ve never had to deal with taxes and health insurance as an independent contractor before.
Would love some advice from anyone who has gone through the process before.

I used healthcare.gov last year while I was unemployed and was pretty pleased to have enough subsidized coverage to have a very basic health plan for $0 (It’s not a good one, but I guess for really extreme situations it’s fine. But even when I was full-time and had “good” health insurance, I paid insane amounts.)

But now that I have income, I’m being asked to provide it – specifically for December. This is frustrating because I’m working much more and getting paid much more than I would any other month due to the College Essay Writing bonus (literally a $6-$10 hourly bonus). I guess I should just be truthful, but if it tries to average it out into some sort of every-month estimate and I no longer get subsidized health insurance, that just doesn’t seem fair.

Additionally, I work from home so I do not have to include “business expenses.” Based on what I googled, that can include rent and utilities for whatever percentage of space your office takes up. I don’t know how to calculate it, but I have a tiny apartment where my “office” is the main bedroom. So should I just guess maybe 35%, add my electric and rent together, then calculate 35% percent and subtract that?

Thanks in advance. I’m feeling super clueless so any feedback is appreciated.