I know I’m not fat but.....

The first pic is today, after a day of eating a lot. The second is a month ago. It looks like I’m sucking in my stomach but it was just taken in the morning before ive eaten. Why do I get soooo bloated every day?? It makes me not want to eat and every time I eat an extra dessert or snack I regret it soooo much. I don’t want to be like this and I know I’m not big but im so insecure about my body all the time. What can I do???