O.K. I feel ya! I am of the same African Heritage as you. It is a fact the American/Western diet does not work well with the African or Latina/Latino body.
Concerning self image: It doesn't help that they are always showing skinny Caucasian girls with long flowing hair as the icon of beauty. If you will notice it is
not just a black thing. When Latinos come to America they start to swell too.
Diet: When I travel to West Africa for just a few months I lose weight. Even though I eat almost the same things. I believe it is because I drink more water when I am there and I sweat. The chemicals they use to make and grow the food in America also plays a great part. Try drinking more water and eating more fruits and veggies. If you are doing these things try eating organic foods and food that has not been treated with fertilizers and growth hormones. Also, TURN OFF THE AC in your car, house, everywhere.
SWEAT A LITTLE! Appearance: I know you want to look beautiful on the outside. It can be hard to do that on a budget. It is also hard to find affordable clothing that fits our curves and butts but I wouldn't trade my Donk for a flat butt anyday. Neither would they. That is why so many of them are purchasing padded buttocks.

Concerning dark skin: Girl, what is wrong with you? You should know more than anyone else that black comes in all shades of beautiful! Stay away from the bleach. If you are toning up a major skin discoloration or scar that is one thing. Otherwise stay away.
Short Hair: If you can't find out how to make short hair look good, check out some YOUTUBE videos. Natural hair is in and will always be in! If money is an issue visit the beauty schools and get your hair done (HAIR DID..LOL.) for a fraction of the cost.
Final, get a Spirit, mind and emotions make over! Girl, you are worried about your exterior but it sounds like it is your inner man that is in need of the REAL MAKEOVER.
Charm is deceitful, and beauty is vain: but a woman that fears the LORD, she shall be praised. Proverbs 31:30