Not to get too personal on you, but I've struggled with the same - I hope this doesn't get super preachy, but this is just some stuff I've picked up? Clearly I don't know what you look like, but I will say that that "flab" that appears when people sit down often
is something completely necessary. Most people have it (all to a certain degree, actually - if you didn't have at least a little skin folding/bunching when you sat down, your skin would tear as soon as you went to stand up).
It's not necessarily unhealthy to have smaller portions, especially as the day goes on (by dinnertime I believe you actually require less food because by all means you should be going to bed a while after, which doesn't consume as much energy, but don't quote me on that). However, you should make sure that you're still getting all the nutrition and caloric content you need, because it
is really important that you maintain your diet so that you have enough calories to sustain you throughout the day - and if you do want to lose weight, eating too little can actually lead to metabolism of muscle tissue, so you're actually not going to lose any adipose tissue at all, just the stuff you actually need.
Also just a reminder that you can't
always rely on the scale - it's a useful indicator of some things, but there's some stuff it just doesn't tell you. I know for a fact that I've been getting unhealthier over the years since I stopped exercising as much as I used to, yet I've lost weight, since what I've been losing is muscle mass. Ultimately it's not really about minimizing the number; I know everyone and their aunt says this but the ultimate goal is staying healthy. I'd just say not to prioritize appearance as much (though I know that's a lot easier said than done, sorry) and just focus on how you feel: if you feel healthy and alert and physically sound, I think that's a better indicator than anything else.
I think this did get a little preachy, so I'm sorry about that.
But I've definitely had the same thoughts, so I just figured I may as well say something since this stuff has been on my mind a lot recently.