Am i losing weight/stmach fat?

Im 14 5 8 144lbs well i think.ive ran for 30mins this past week uphill and lots of downhill alot this week and today when i woke up and sto9od up i touched my stomach and my stomach felt tighter in a good way as if i was losing some fat. I dont have that much but i would just like to have a flat stomach.I eat healthy and only drink water now.Am i losing stomach fat also i run at my trtack but mostly in my neighborhood.Theres tons of uphills well thats mostly what i run so do i burn mor calories by doing so? Thanks and im maintaining to a heaslthy diet & i also run track and starting XC next month.