Metabolism issues...help?

My first year of high school, I took a health class that convinced me that I needed to loose weight. I'm 5' 6.5" tall, and weighed 148 pounds. Most of my friends didn't believe that I weighed that much, and said it was just muscle, but I felt really uncomfortable with my weight, so I began watching what I ate.
At first, I limited myself to about 2000 calories a day, and relied on the dance classes I was taking and marching band to supply a decent amount of exercise. That worked for a month or two, but then I took it to the extreme...at one point I was only eating 700 calories a day. That phase only lasted a week or two before I came to my senses, and went back to about 1800 calories a day.
I did lose weight...by the fall of the next year, I weighed 128 pounds, and was quite proud of myself. After a month or so, I began to gain weight back. This made no sense to me, as I was eating what seemed to me to be a sensible amount and exercising regularly, but I reduced what I ate to 1500 calories anyway.
It didn't work. Now, I weigh almost what I did to start with (now 142), , exercise every single day, and can only eat 1200 calories a day, yet I am still slowly gaining weight.

My mom is convinced I have some sort of eating disorder, but it's no form of anorexia or bulimia, as i never flat-out starve myself or anything to that effect, I just watch what I eat really closely...too closely she says. She tells me I obsess over it, and exercise more than is really healthy. "You shouldn't be constantly concerning yourself with what you've had to eat and when you'll get the chance to exercise every day," she tells me. I don't see how one can't without gaining weight, though.

Anyway, one thing I know is that I've thoroughly screwed up my metabolism. My mom found a list of possible side effects to not eating enough (including trouble concentrating, feeling tired all the time, etc.) , and most of the things on the list were things I've been complaining about lately. Doctors have told me, too, that I should be eating about 2000 calories a day, but I can't without gaining weight.

So my question is this: Have I messed my metabolism up permanently, or is there a way to fix it? If there is, how much weight am I going to have to gain in the process, and how should I go about doing this?

Any advice would be beyond greatly appreciated...

Eat what your doctors are telling you to eat.  Your metabolism will fix itself then.  At 148 pounds you are within the normal range for your height and are not overweight.  Assuming you're still a teenager, you NEED to be eating more.  So do what the doctors say.  :)

I've heard of people who started losing weight after they upped their calorie intake. Maybe that is the answer to curing your metabolism! Goodluck

When I was in high school I did almost the same thing you did. I weighed 170 and decided it was time to get healthy. I gave up fast food and soda and started exercising 5 days a week. It worked. I was eating a healthy 1800 calories a day. I didnt count back then thow, thats a estimate. Then I took it to the extreme, slowly I started reducing my calorie intake more and more and exercising more intense. I ended up getting very ill and depressed. I stopped exercising from lack of energy and I was stuck like that for about 2 years. Then a year ago, I decided it was time to get better. I started eating more and healthy. Naturally, I gained weight from eating more. I gained 35 lbs!! I went from 115 to 150. I did not plan on gaining that much. It just happened because for 2 years I had ruined metabolism. I thought I was stuck just like you feel right now. So I did research and I read lots of other peoples posts on calorie count. I started eating a much cleaner healthier diet and exercising again to get my metabolism going. For 2 months now I have been eating 1600-1800 calories a day, along with weight lifting and cardo, 5 days a week. It is a  VERY slow process, but I am beginning to see some changes in my body. So hopefully soon the number on the scale will change too :) Be patient! Treat your body right and in time it'll happen :)

yup there is a way to fix it,by upping ur calories slowly and maintaining it at healthy amount. i was on a 1000-1200 cals per day diet for several years. now i realise that i should be eating 1500 at the very least. I've upped my calories...now i think im consuming an average of 1400-1500 cals. i weighed myself in the first 2 weeks and my weight increased by 3 kg! i panicked. however,when i weighed myself a week later,it went down to 56 kg,still 2 pounds more than my original weight (55 kg).my goal calorie intake is 1650-1700 cals so i hope when i reach that, i'll lose the weight. so yeah,expect weight gain at first,but stick in there, and ur body will adjust.