I need your help

Hey guys. Im 13 and i need to k ow why i randomly woke up with extra fat. And i always feel full when i eat. And i dont normally have this problem. And i jist got my first period december 9th to 15 then it skipped a month amd got it February 5th to 10th. And i wanted to k ow why i got all this extra fat? Im stsrting a workout routine and i just need help. I convinced myself i was pregnant and putting bad thoughts into my head. And i wanted to say also my period was really really light..😒 i could use some girl talk right now