Too big, too thick for what? You can't compare yourself to anyone else, especially Photoshopped images in mags and celebrities in the media. Do you have a team of people dressing you with custom-fitted clothes and doing your hair and makeup every day? It takes a lot of time, work and effort to look like that. Just look at those stars without makeup photos. Most don't look so hot.
You are a realization of your own unique genetic destiny. The blueprint for you was set at conception, everything from the length of your bones, the insertion points of your muscles, the type of muscle fibers, number of fat cells, etc. Sure, external factors my influence some things like fat cells or diseases that affect your body's development. But for most of us, we are unique.beings with our own potential.
My goal is to always maximize MY potential and to be realistic about what that is. I am short. My hip bones and the bottom of my rib cage practically touch. No matter what I do, I will never have a long, narrow waistline. I am strong and very muscular. I would actually have to loose muscle mass to fit in the BMI charts. I will admit that these things used to bother my more when I was younger, but that ended when I started focusing on what my body can do rather than how it looks.
I have thick thighs and a round butt, but it is exactly these attributes that allow me to pedal my way across states and in 100-mile rides. I have strong arms, but they allow me to turn my backyard into a vegetable garden. At 50, I look around and see so many who have not taken care of their incredible bodies and are now paying a price. I can't imagine just having so much difficulty getting through the tasks of daily living.
Just think about the amazing things your body does for you every day and celebrate that. And then pick clothes that flatter your body type. You'll never find me in skinny jeans because I look like a stuffed sausage but I can rock a boot-leg flare. Make peace with yourself. Your body is all you have and if you treat it right, it will carry you through a lifetime of adventures.