Hello,
First of all let me say that I'm sorry that your're feeling so strongly right now.
You had surgery a week ago. Is it possible you're feeling the effects of the anesthesia coming out of your system? I know that about a week after I come out, I have wicked scary nightmares.
Perhaps the reality of what you've commited to is freaking you out. Sometimes we go into situations with a rosy 'all is great' feeling of what we're doing, but then when the actual day comes, we freak out.
How much research did you do prior to surgery? Did your doctor have you attend seminars and did you visit the lap band forums? If not, then perhaps now would be a good time to review these and read about the success stories of the people here.
You're only 19, and this surgery is a big step, but congratulations to you for doing it while you're young. And congratulations to you for recognizing the need to get healthy while you're at the beginning stages of your life. You will not suffer the needless pain of 20 or more years of being overweight, and hopefully not suffer years of pain and other complications associated with excess weight.
You will not go through years and years and years of unsucessfull weight loss programs and feeling like a complete failure because you can't lose even 10 pounds on carrots and Water.
What I'm saying is that even though you think you made a mistake now, and even bigger one would have been to do nothing.
Keep patient and focuse on the reasons why you've done this. There are minor inconveniences with the band, but there are major inconveniences without it.