Summer weight loss/exercise help for a 14 year old?

So im 14, female, 5'5 1/2, and about 136 lbs. I know, Im fat... but by the end of summer, I want to weigh about 122. Ive lost some weight already, at the end of april I weighed 145 or so and then i only rode a bike for 45 minutes 3 days a week.But now that Ive lost 10 lbs I still feel I need to lose a lot more and I have more time for exercise now. So Ive been following a plan of 1800 calories a day and for exercise Ive been doing a 45 minute bike ride 4 days a week, and running abut 1.5- 2 miles the other 3 days. I been doing that for about 2 weeks now... but ive only lost 1-2 lbs and i gain it back really fast. Am I eating to many calories? I have this weight loss thing on my phone where you enter in all the weight you want to lose and what exercises you do, and it says I should eat 1900 calories a day! That seems really high.. so like I said, I only eat 1600 sometimes I have more, but if I eat a little more I end up eating everything in my kitchen, haha, but should I lower my calorie in take? And also I have some questions.. is it bad to eat a peanut er sand-which if the peanut er is jiff? Like my mom doesn't buy the healthy stuff and I love peanut er so I take a slice of bread and put a banana or honey on it. And how much weight would you recommend I lose? Is 12 lbs enough? Thanks, and can you not say I should take diet pills or a paid diet program, my mom would never let me do that.