Well firstly, remember that you/ what you are is NOT your illness, or your anger issues. YOU are whoever you want to be- you have flaws and weaknesses- but you also have talents, skills, and unique interesting traits that make you a unique person.
you are not your anger/ mental health issues. They're something that you got stuck with- you didn't choose them nor do you deserve them. Try to practice some compassion to yourself. Beating yourself up endlessly and calling yourself makes or thinking you're horrible is not a kind thing to do to yourself- so try to remember that it's your ILLNESS that's making you act like this, it's not truly who you are.
How do I know? Because you care- there are lots of people who are angry and yell and they don't care- that's who they are and they're not concerned. You are- so much so you're posting on a forum asking for help because you don't want to act like that! Please take some pride in that who you truly are wants to win over the illness!
have you accessed your mental health care plan through your dictor, so you can attend therapy for free/ cheap? Have you spoken to your dictir about whether your meds are correct- maybe something different might help?
you may have had bad experiences or not found theraoy useful, but there are tonnes of therapists out there- you may find someone who "gets" you, and whose strategies you find very helpful.
irritability, anger and hostility can certainly be synptoms of a mental illness, Wheh I had bad deoression I was always "snapping" and "expding", then id really be angry at myself for "being a horrible person". Actually that only made me more angry and the cycle got worse. So be forgiving!
Therapy strategies, compassion to myself, and understanding helped me. Eg I learned to watch for early signs that I was getting angry and heading towards an "explosion" and I found many strategies to put that energy somewhere else
i LOVE intense sport (eg crossfit, martial arts) as it channels the frustrations and pent up energy into heakthy exercise- I do it most nights as it releases all the tension of the day so I can sleep well and start a fresh, calm day- it never has a chance to "build" when I get it out like that.
i also love blasting music that helps me express it by singing along loudly. I also learned the drums too!
Instead of trying to "stop"- channel that energy somewhere healthy and you won't snap at people!
