Are you male or female? Because that does matter. However 205 is quite a bit for either sex, so you are medically obese. Have you ever had your fat percentage looked at? This is usually done at a dr's office, they measure your fat rolls. Being 12 and pushing 6 ft I'm assuming you're probably male and hit puberty early so that could be a lot of muscle weight. Are you built like a linebacker? If you are you might want to talk to your doctor or school nurse to see if you need to loose weight.
If not.. you almost definitely need to loose weight. I'm not trying to be mean, I was once almost literally in your shoes. I was 160+ at 12 and only 5 ft even. 12 years later I have high cholesterol, high blood pressure, gallbladder problems, exercise induced asthma, knee and foot problems, back problems, and a huge risk for diabetes and heart disease. Honestly most of these problems started in high school, so now is the time for you to get in gear-before these health problems start.
Get your thyroid levels tested. Your thyroid is responsible for a lot of your metabolism so weight problems can many times be traced back to a thyroid issue. The doctors will test you for your TSH level, this is a signal hormone that tells the thyroid to work and is best used as only a screening test. So ask your parent to push for the Dr to test your Free t3 and T4, these are usually much better at telling you what your thyroid is really doing.
Talk to your family about trying to cut back on the junk. Talk to your doctor about being set up with a dietician. Note this last one is kind of important because you're young so you have to be careful on how you loose weight.
Join a school or church sports team if you can. I know these can get expensive, but if your family can pay for it it will help keep you active which will help boost your metabolism. Also never fear no one expects you to be a pro or will make fun of you if you aren't. A lot of school sports should be played just because they're fun. Although, you never know, you may have an unknown talent hiding.
Some basic food things that might help:
Stop drinking soda, energy drinks, cool aid, etc. Your body needs fluids but all that extra sugar is really just stuff your body doesn't need. Replace it with 100% juice, reduced fat milk, and lots of water. Same with sugary snacks and chips- replace these with fruit, yogurt, or nuts.
Make sure you never miss any meal!! It's important to eat at a similar time every day and keep your body happy. This usually means eating more than 3 times a day. So you have your breakfast, lunch, and dinner.. but you also have a good low calorie snack between meals. Personally I like these to be fruit and keep them at less than 100 calories. If you can't have one between breakfast and lunch, make sure you at least get one after school. Also the trick is not to eat until you're full. Just until you're no longer hungry. You eat more often, but you're usually eating a LOT less calories.
Fried foods are a no go. If your family eats out a lot that's a lot of calories, sodium, and fats. Not good for your body at all. You need to try to eat lean protein -like fish, seafood, eggs, beans, low fat dairy, or chicken. (And frying or breading these lean foods doesn't do them any good.) Also stick to good fats- avocado, nuts, sesame seeds, low fat dairy, olive oil. Try to fill half your plate with good leafy veggies- broccoli, cauliflower, green beans, carrots, artichokes, etc. Also be sure you're having some rice, pasta, or bread on a daily basis- try to get these to be whole grain if you can.
If you can't get your family on tract to eat healthy try to either learn how to cook, or learn how to order. Basically you walk into Subway, what do you get? If you pile on the meats and cheese, you pile on the calories. If you add a ton of sauces, you could be adding lots of fats and sugar. If you follow that with a cookie, chips and/or soda... well then you might as well have something fried for lunch. Good rule of thumb- look for something grilled on a menu, take off the sauce (maybe add your own so you know it's not too much) and pile on the veggies.
Just keep in mind that you're beautiful the way you are, but you DO need to eat better and maybe loose some weight so you aren't setting yourself up for the kind of health problems I have. It's hard to be the fat kid when you're young, but as you get older things just get worse. Every added pound and every inch makes it harder to move. While it starts out that you sit out on the sidelines from your friends because you are embarrassed about how you look- it gets to the point where you are sitting on the sidelines because you don't have the energy or strength to participate. Just please seriously consider getting healthy because I can tell you 12 years later- I'm not doing so hot (and this is AFTER I lost 35 lbs that I'm telling you this.)
I am a female but my doctors keep on telling me that it is my height so since i am 5ft 8in
You are very tall so it might be normal for you. The BMI calculations is good for a lot, and many use this to say if someone is over weight or obese. Using it alone, you would probably be considered overweight. BUT it doesn't work well for everyone and fat percentage (how much muscle to fat you have) need to be taken into account.
I would go with what your doctors are telling you on this one. Mine had no hesitation to tell me at 10 that I needed to start loosing weight and eat better. That's a hard thing to tell a kid, but it's their job. So if you were in danger with your weight they probably would tell you. It's still important to eat healthy though- no getting out of that one.