Hello dear student,

As you said you have done commerce in your class 12th so you are not eligible for BSC in psychology why you can do BA in psychology. Bsc stands for bachelors of science why you did not have science in your 12th but doing commerce makes you eligible to do BA which is bachelors of arts.  Here I am also attaching a link that will be helpful for you for further information

https://www.careers360.com/courses/psychology-course

Thank you