5'11 with weird measurements, what am I doing wrong?

So I'm around 5'10 1/2 and 5'11, and I weigh between 155 and 160. My weight fluctuates everyday. I work at Illinois largest waterpark almost everyday between 8-10 hours. During the winter I plan on lifeguarding at a nearby YMCA. All my life I've grown up with big thighs, big hips, and a tiny upper body. My waist is around 25-26 inches, my hips are 40, and my thighs are 22-23 inches. I've been made fun of a lot when I was little for my height because I was 5'6 when I left 4th grade and that's when I started going through puberty, so I grew really fast and was done growing physically by 8th grade. So I've always believed I was chubby. I eat healthy, I work out all the time, I work outside for many hours, but nothing seems to be doing it. My weight always fluctuates from high to low. I just recently made a Myfitnesspal to track what I eat and do now, so maybe it'll help. But does/did this happen to anyone else?