US Immigration from Japan

I have my tax returns for 2020 and 2019, but did not file in 2018 (I was a student and not working). Do I check question 25 (under part 6), or is that only for if I didn't file in the most recent tax year (2020)?

I've looked everywhere and cannot find a solid answer to this, so any suggestions would be very appreciated.

A decent size of my income is based on commission. As such, I am not sure what to put for part 6 question 7. I've been in my position for a little over a year, and have one tax return (2020) for this role. Should I put my target annual compensation (base pay + commission at 100% of my goal), or should I put total income listed on my 2020 tax transcript?

With just my base pay I am above the required amount, but not by a whole lot so it would not be great to put only that I don't think.