Why am i so violent when drunk, and sometimes sober?

Since i was about 16 ive been gettin in trouble with the law when pissed up. nothing too serious, abh criminal damage drunk n disorderly etc i thought id grow out of it but im 21 now and nothings changed. I calmed down a bit when i was 18 but then i moved down south for uni when i was 20 and got worse again. I battered some bloke in the same week as moving down there, not a hospital job but a bust nose and a cut eye, then i hit another bloke in a pub, just the once not quite a year ago, then last night i beat up some polish man, wont go into details but he was pretty bad after. dont wanna say where im from in england but like most places its a bit violent, people love scrapping. Ive not had a rough up bringin but have had a fair amount of **** to deal with, ive lost a gf because of the violence (not towards her)and its not my personality, im actually a sensitive person n have never been a bully, never started on a weak man. Is it caused by alcohol or just fueled by it, does it run a bit deeper than just bein a rowdy drunk? There are literally too many incidents to mention, but it ranges from, fightin bouncers, smashin windows, jumpin taxis n just basically bein a ****. its embaring and im not a kid anymore and need to sort it but im not sure how, im worried i'll go prison if it carries on, pretty sure i will, i'd already be there if old bill knew all the things i've done. I keep appearing in court and they're only gna fine me so many times. anyone got any advice or have maybe been through the same thing? I've tried working out, boxing and thai boxing to get the anger out but it dont help, it just makes me a better fighter