I get you. I haven't SI for about 3 yrs but it's a journey to help you recover.
when I started I was 14 and no one knew till I had a nervous breakdown at age 16 1/2.
I secretly SI for 2 1/2 yrs but it leads to a horrible path of lies and inner pain.
I had a HUGE nervous breakdown at age 16!! Not a good thing when dealing with SI.
I ask you to seek professional help as well as making your family a support system.
My mom was an angel to me and got me good help.
People who are addicted to SI are usually diagnosed with a personality disorder
and BPD or major depression.
Medication helps even if it sounds cliche.

I'll pray for you...
I really hope you get help before a more worst thing happens.