It could also be a thyroid disorder. Side effects can include sleepyness, lack of energy, depression.
Eating right and exercising is great advice, but this sounds more serious to me. You've said you've been like this your entire life.
Do not let the doctors push you around. Keep right on hounding them to make sure they're doing their jobs. Get a second opinion if you need to. I've been to so many bad doctors because I'm in an HMO, so I know how to handle them. This really sounds like a medical problem.
Eating right and exercising is great advice, but this sounds more serious to me. You've said you've been like this your entire life.
Do not let the doctors push you around. Keep right on hounding them to make sure they're doing their jobs. Get a second opinion if you need to. I've been to so many bad doctors because I'm in an HMO, so I know how to handle them. This really sounds like a medical problem.