I'm been taking Concerta for my ADD for 2 1/2 years. I'm 16 years old, and female.

Anyways, on to my problem. I've noticed that whenever I'm on Concerta, my metal process is completely different. The way I think, the way I act is completely different from how I am when I'm off of it. I know this isn't uncommon, for a person to become zombie-ish when they are taking meds for ADD, but it almost seems like I have split personalities now.
Let me explain...
When I'm on Concerta, I have pretty bad amnesia almost. I can barely remember what has happened when I'm not on it. For example: I don't take Concerta on the weekends. I'm rather happy, and I'm sure I go out and do things. But come Monday, once I take my morning pill, there's this blank spot in my memory when I try to recall the events of the weekend. Sometimes I can remember small things. Like last weekend I drove to the bookstore. But that's ALL that I remember. Everything else is either black, or one big blur.
I also have a huge problem with remembering emotions. Memories that I have are blank and emotionless. I have to literally think to myself, "During the event I THINK I had a good time. I must have been happy." But sometimes my logic fails, and people tell me, "You did this, and you weren't happy," or something like that. Sometimes when people tell me about events that I've forgotten, I get like flashback-sort-of-things, and I'm like, "Oh! I remember that!" But most of the time, I still draw a blank. I have to trust their word.
When I'm on Concerta, I can remember facts, and stuff that I've done while I'm on the medicine! But I draw a blank when it comes to stuff that happened while I'm off it.

Now here's the other weird part. When Concerta is wearing off, I can tell that it is because I begin to feel much better, and completely different. I'm emotional, happy, able to laugh, ect. I NOW can remember what I've done and felt on those weekends, that I couldn't remember before; but now I can't seem to remember what I've done or said when I was on Concerta! Once again, I can make out some things, but everything is one big blur. I have to make predictions about myself, and what I did, and how I thought. I didn't realize the extent of this amnesia till yesterday though.
Yesterday, I was having a very serious conversation with one of my friends. Even on Concerta, I was a bit emotional about it. I was angry, and I had good reason to be! But then all of a sudden, I found something funny, and I laughed. It was the first time all day I had done so... And then I began to feel this being weight lifted off of me. I was SO happy that Concerta was finally wearing off. (A part of me hates being on it.) Anyways... my emotions started to change, my way of talking was different, and I went from being angry at this person, to feeling bad for making them feel bad for something horrible that they had done to me. But when I tried to think of what they did... my mind went blank. Whatever the problem was, I knew that it was important, and that I had good reason to be so angry over it before; but now I just couldn't remember. Just like that, in a matter of minutes, from being on Concerta to having it wear off... I experienced this amnesia.
That's when I realized that I basically have the symptoms of multiple personalities or SOMETHING like it, but I know that Concerta must be the cause!

This amnesia is so frustrating... I can barely remember my life, and it seems like it's just flying by. Remembering the past is like remembering a dream... and I don't like it.
I can remember facts and formulas and information perfectly, but when it comes to events, and emotions, I draw a blank.

Anyone else have this problem?
Any words of advice?

I'm going to the doctors on Friday.

EDIT:
I'm on Concerta right now. I'm sure that when I look at this later tonight, it'll feel like this was written by somebody else. But quoting my thoughts, when I'm off Concerta, I think very highly of myself when I'm on it. It's quite weird actually...