I'm on a diet, but why does my belly look even bigger?

I've been losing weight little by little lately while controlling my diet, but strangely, my belly looks the same or even bigger, so I'm worried.

At first, I wondered if my belly fat just wasn't coming off, but as I changed my diet and ate more vegetables and protein, I feel like I have more days with gas or bloating. My stomach looks especially bulging when I'm constipated.

Has anyone else experienced a situation where other parts of their body slimmed down while dieting, but their belly specifically didn't shrink or appeared to stick out even more? I'm curious if it's simply that abdominal fat isn't going away, or if gas or bloating is caused by dieting. In such cases, I'd also like to know how you adjusted your diet or exercise.