I'm the same way. I'm not hugely overweight (6'0", skinny frame, 188 lbs). I'm also using MFP to track this stuff, and I had the same appreciation about truly obese people the moment I saw how much I was really eating. I had that same, "wow, I should be much fatter than I am!" thought.
The only reason it has taken me this long to change is because my 20's body was able to handle whatever I threw at it. My 30's body now is not so capable.
it was basically the 'am i or am i not going to seriously be a lifelong fatass. like for real though.' point in my life. like you kind of know, if i let this slip a few more years, there's probably no going back.
i'm also doing weights with a trainer and that has drastically improved my general appearance, especially in my upper body/shoulders. simply losing weight would have produced a weak and skinnyfat version of myself.
i think 3k is where most people in the US eat at. it's basically the pointless snacks and carby/sugary crap that make the difference between 2k and 3k. that extra 1k calories is easy to eat, and hard to cut.
quite honestly it's amazing i didn't weigh 300 pounds... a lot of people do weigh 300+. being overweight (and i still am over by about 15 lbs, slowly losing the rest) gave me a serious appreciation for the bad psychological state one must be in to really let it get that bad.