I don't believe you have a problem that is bigger then 15 to 20 pounds. My wife is 5' 6 1/2" at 155.....sizes run generally10 to 12. With only a half inch and five pounds difference you can't be that bad off.
Some folks loose extra pounds by counting calories,
some by counting cabs.
Others talk with they're doctor and come up with a program of diet and exercise.
I would suggest the later. And as I tell my granddaughters......
YOU CAN DO IT!! soapbox