Hii!
You haven't mentioned the name of the course you are interested in, to pursue B.A in. You haven't mentioned the percentage marks also, you got in class 12th. But, let me tell you, if you seek admissions in DU, from this year, no marks will be deducted for changing the stream.
Also, you can go for the improvement exam in atleast 3 subjects and improve your percentage marks. Now, after that, when you become eligible for getting a seat in your dream course with good marks, you can apply for the course.
If there's anything else you need to know, feel.free to ask in the comments section.
Hope this helps.
Good luck!