OK. Next time you see your physician for a general health check-up, you might want to discuss weight management.
In the meantime, you need to become knowledgeable about nutrition and exercise.
I do not know what you do or do not know about the subject. So bear with me.
Your body will want to gain weight naturally. This is a survival function and occurs without you even thinking about it. So, to lose weight (and then, ultimately maintain a good weight) you need to think about it and stay on track with diet and exercise. It sounds like a lot to do and think about, let alone the difficulty staying on a good nutritional diet. But with time and practice it will become second nature to you. And you will be grateful for it all of your life.
Basically, your body will store any calories you eat that are more than what you use in a day (or even a few hours). It doesn't matter what the calories are composed of (protein, carbohydrate, fat.....), they are calories and need to be used, or they will be quickly stored.
You will want to determine a good "diet" for yourself. Food is to be enjoyed, but most of us "enjoy" way to much of it. Practice enjoying small portion sizes instead. Portion size is the number one cause of obesity in America. Many foods, even sweets, are OK for you to eat in the correct portions.
For a guideline about what you need to eat every day, here is a link:
Mayo Clinic Healthy Weight Pyramid tool
Just fill in the information about yourself, and it will give you a food pyramid that will help you accomplish your goals. You need to eat everything listed in the pyramid to make sure you are getting the correct balance of nutrients. Otherwise you will not be able to lose weight as the diet intends. Note that you can have some sweets; and you can have extra servings of non starchy vegetables and fruits. You can print out a 4 page document that lists foods and serving sizes in each group.
Here is another link:
This if free to use, and will give you calories, proteins, fats (and type of fat), carbs, sugars, fiber and other nutritional information about just about anything, even some restaurant foods.
The key to a successful diet is not to think of it as a diet, but as a lifestyle. You want a healthy lifestyle because it will make you feel physically and emotionally well. We all want that.
Before you eat anything, know what it contains nutritionally. This is hard at first, but with practice becomes easier. Read labels. Choose your foods carefully. And most important---track you intake and progress. Use whatever means suits you (notebook, scrap of paper, computer, IPhone...whatever) to list the foods groups you will eat daily, then tick them off as you eat them. When everything is ticked off.....you are done for the day. But with the Mayo diet, if you get hungry just eat more non starchy vegetables and fruits.
Drink plenty of water. About 8 cups of water a day, or more. Evaluate your beverages of choice. If they have extra calories you don't need, change to something that does not (or drink water instead).
Watch sodium as well. Too much salt can make you retain fluids, or will keep you from losing the weight you want to lose. You should stay at about 2300mg per day or less. Write down how much sodium you eat with each meal so you stay on track.
For exercise, start by simply getting physical whatever that means to you. Start walking...30 minutes minimum a day to start and work up. Get a bicycle. Walk to the corner store instead of driving. Join a gym. Many have programs where you can start free for the first month. Whatever it is you choose....do it every day.
Track your progress. Along with writing down everything you eat, note your weight daily. Women can go up and down a little from fluid shifts caused by hormones, but generally if you stick to your plan you will see a gradual reduction in weight.
Here is another link with some beginning, general information:
Aim for a Healthy Weight
There is a BMI calculator at this site as well.
Pretend that you are going to school to earn a degree in nutrition and weight and health maintenance. Look up things you have questions about. Sign up for sites that send you daily emails with nutritional information. Go to the library. Whatever you like, but read and take notes. Perhaps local health facilities will have talks about weight control. Maybe you would like to join an organized weight management group such as Weight Watchers. But make this your mission in life for now.
One day, you will know everything you need to know to keep yourself trim, happy, beautiful (on the outside as well as the inside), and healthy for many years to come. This is quality of life. It is well worth the effort.