Lost

Let’s try a therapy here.
Point the reason for stealing.
A- can’t you afford it,
B- it’s compulsive or
C- your reason.
After, you have to notice how do you feel when you steal?
How do you feel when you lie?
Your conscious say to you it’s wrong and then you become sad after doing it.
But what about when you are doing it, what is the feeling, adventurous, courageous, I can’t get caught, feeling clever other feelings that you can name it- these are just examples.
These action can be related to your subconscious, a change of mind that occurs and your conscious can’t block amd you do what you.
Later after your conscious realize the actions amd starts to judge yourself, it hapoens due to the moral and ethics that we all have as a society.
But if we return thousands of years ago, humans are beings created to hunt, to have their own territory, saying this realtes to the fact that our society evolved but our bodies don’t, so as our brains.
An example of it is that women, most of them that relates with that part of our ancestral brain, look for strong and violent guys, why? Because those women look for the strongest mate their brains point to to have strong and health babies.
In your case your brain, mostly your subconscious makes you do those things in an alternate state of mind.
To recognize it try to see how your brain differ from you normal state to when you are in motion ti steal our lie.
Now some advices, if you steal try to give it back when you can, without being caught.
Being in a boarding school can be very traumatic if they find out, they will judge, exclude and bully you for the rest of the time you have to be there.
Don’t let it happen or you will feel so broken that you might commit suicide.

Look for help, think about what I said.
Good luck.