should I eat more?

Hi
I (male 33 years old 178cm) have had a little belly for quiet a while without being able to get reed of it
I usually eat a lot, specificaly carbs
for the last month I tried to reduce my kcal intake around 2000kcal a day and eating more proteins using foodvisory and trying to figure out the kcal I burn a day, which it seems I eye balled it way way to low...
let me explain
I am a bike courrier and I ride a cargo bike with ususally around 60 to 80kg of loads
today I used a chest heart rate monitor with the polar beat app to see how much kcal it said I consumme a day... turns out counting the kcal I use during my shifts and my base metabolism for the rest of the day I am more around 4000 to 4100kcal a day

I used to not be super on point on my protein intake, and I am wondering if maybe to finaly loose my belly I should eat more to lower my cortisol levels and a better protein intake to maybe get out of a survival mode my body is in?
any advises?
(I do boxing 1,5h a week and recently started to go the the gym on my days off)