Venting out my problems...

I(21M) dont usually share my problems but lately feels like im in a crisis... Nothing seems to be working. I am addicted to cheap dopamine and small term gratification (which i do through constantly scrolling, watching porn, etc) and after i do that at night i resolve to not to repeat that by any means but the cycle repeats itself... sometimes i feel like im not myself anymore.... am in the last year of college and am preparing for a very tough exam to earn my dream life but it is feeling like i just am myself pulling my own leg from the ladder that i want to climb... it is always my brain which creates its own problem... and doesnt let me work even if i am willing for it ... everyday i have to go through this phase of dissappointment of not reaching my potential (or not even half of it)... everyday at night i feel like it would be the last day and that tomorrow will be brighter but i somehow find myself ended up in the same miserable place... Thank you if you are reading this if you would like to add on this or suggest me anything please do.