Feeling horrible in own skin

I feel so mad at myself idk. Im not even fat or anything but I still have stretch marks on my hips and it makes me feel so bad.. I've never had any kids or anything so there's no excuse there.. It makes me feel like I'm eating too much and stuff. Like yeah I am growing from eating a lot but I'm not overweight .. I don't know what to do 😔 I work at fast food and have to eat there for breaks otherwise I don't eat at all and I'm gaining weight from doing this :/ I'm still a teenager so I feel gross looking at others my age 😪