Which stream you have selected

That's great! I'm glad to hear it 'cos this subject has always kept me enthralled and this particular field can furnish you with wondrous careers in future.
Well, as of now, focus on your respective subects. It doesn't matter in what stream you pass out 12th. Eligibility is just 10 + 2 or any other equivalent examination. Below are best colleges offering B.A. (Hons.) in Phychology:
1. Christ University, Bangalore
(This uni has topped the charts according to the Best Arts College survey conducted by INDIA TODAY in this year)
2. Lady Shri Ram College for Women, DU (Tho' I'd opt for this one if I were a woman)
3. Jesus and Mary College, DU
4. Gargi College, DU
5. Benares Hindu University  (BHU), Varanasi
P.S.- Admission to all the aforesaid colleges except BHU is based on BFS (Best of Four subjects) cut-offs. But, for BHU, you have to appear for BHU UET (Undergraduate Entrance Test) for B.A. (Hons.) Social Science. And, lemme tell you, this exam comprises of other social science subjects too, namely Economics, Sociology, Anthropology, etc. You can prepare for it from ARIHANT'S BHU UET book.
Remember, Physcholgy isn't just science, it's a social science. It has a way lot to do with Economics n' a bit with the discipline of Sociology too. All these are neither Liberal Arts subjects nor completely Science (tho' many globally revered American Universities offer you B.Sc. & M.Sc. in Physcholgy), hence, there's not any compulsion to study a specific stream in +2 to pursue this course. You can ev'n opt for it being a commerce stud.
Hope it helps!

You must have PCB as your main subjects, if your college offers psychology as a vocational subject, you can take it.