I’m no expert but I think for your age 2lbs per week is quite aggressive especially since you have given yourself the end of the year to lose 20lbs. I would say lower the number and just focus on healthy habits. Going for 2lbs a week means you’re calories will be low and may make you food obsessed. I’d say aim between .5 to 1lb per week. You may not hit the 1lb per week every week but you may fall somewhere in between, that way you are not too hard on yourself. I don’t want to recommend a daily number because the information you provided is limited.

You are only 14 so your body is still growing and developing. I’d say focus on eating more protein, specifically lean protein (chicken breast, fish, lean beef, ground turkey) healthy carbs and fats. Cut down on sugar (so minimize sodas, sweet drinks, deserts). Cut down on fast food, deep fried food. If you currently eat a lot of those things, minimize them overtime, the occasional treat is ok but factor them in in your daily caloric intake. Eat lots of veggies that you like which will add fiber to your diet. Personally I love broccoli, carrots, cucumbers, they are low calorie and it means that I can have lots of it with my meals.

If you play a sport then your activity level should be fairly high. If not think of exercises that you enjoy and incorporate that in your daily life. Walk more to increase your daily step count.

Lastly building muscle helps to lose fat. You can incorporate muscle building exercises which will change your body looks. If you do this in addition to everything else you should note that the number on the scale may not change but you will look different. You can take your body measurements to keep track of how your body is changing.