Hi Liam,
I have had mental health problems before,and I have also been a buddhist for some years.I feel that all religion well not all religion but most is good for mental health surveys support this.Also buddhism is a very therapeutic religion.Nevertheless it may take time for it to work for you,and you may face ups and downs in the process, Rome wasn’t built in a day.About four four and a half years ago,I was in a terrible state.I am better in part due to the buddhism but not only because of it.So I would recommend it whilst remaining patient.The feelings you are expressing have been familiar to me at times.
Best wishes
Paul