Hello Chris,
Welcome to the forum!!
Am glad you’ve registered and made the effort to post and am sorry to hear you’re not in a very good situation at this moment in time. Am sure you’ve heard the first step to recovery from any kind of bad situation is admitting and accepting your current reality. I think you have done that today with us so now all you need is a plan of action to get you on the right path.
If i was you and i discovered Islam is the truth, the very first thing we are all encouraged to do is to recite our declaration of faith. If you have a mosque near you, you can visit your mosque and the local imam (spiritual leader), will talk you through everything and this is a great and fantastic way of meeting. Maybe new Muslims who have recently accepted our faith like yourself? Or even born Muslims?
If this isn’t an option for you we are happy to talk you through the steps.
If you believe there is only One God who should be worshipped, and no one/nothing else has that right but Him, and you believe Muhammad, peace be upon him, was a messenger who brought the same message as all the prophets before him, then you are basically a Muslim.
To become a Muslim, simply declare the following: (If you haven't already done so)
Ash-hadu an laa ilaaha illallaah, wa ash-hadu anna Muhammadan ‘abduhu wa rasuluh.
I testify there is nothing worthy of worship except Allah, and I testify Muhammad is His slave and messenger.
If you wish to read more please visit:-
http://www.kalamullah.com/non-muslims.html
Am glad to hear your family is very supporting, in particular your parents. That's very good to hear.
I would also like you to maybe question and re-evaluate yourself and your priorities. I believe there is always a reason why people turn to drugs and alcohol. Maybe you want to get away from exam stress, family problems, peer pressure, personal problems etc? Whatever the reason, when we're in a good healthy state of mind we all know our problems won't run away. When we 'wake up' from the sleep i.e. the drugs or the alcohol, we return back to the same problem. If not the same problem, a worse problem - because, the problem wasn't addressed properly.
So maybe you can write down your worries and concerns and write down a solution next to the problem. Don't forget to implement the solution :-)
I would also recommend using the gym or going for a jog outside. Most scientists agree by doing any physical activity we release the happy hormone. So this in sha Allah (God willing) will be easy for you.
& when you start believing, practicing, living and breathing like a Muslim you will automatically feel the inner peace and contentment. You won't need any other additional boost. In sha Allah.
Please don't lost hope - it all starts with hope. Am glad you are seeing this as your second chance because maybe it is.
Also visit your local doctor to get a full health check and seek his/her advice on the best approach to get off the drugs and alcohol.
I need to pray now, am sorry if i've missed any other points you've typed. I'll try and come back and advise you further in sha Allah.
I wish you the best and hope you accept Islam fully with heart and mind (if you haven't already) Ameen.