Hi sahana

Changing your stream from science to commerce depends upon various factors. Firstly the school in which you study has to approve for the same. The school looks into account various factors like seat availability, time left for the examination etc before switching streams. Also there has to be a proper explanation from your end for the change. Also if the registration has been done in the respective board then it will be difficult to change. Time is a big constraint for the change as you have to cope up with the new syllabus. Whether you can cope depends upon your IQ level and the time you devote for your studies.But i would suggest you to continue with science till +2 and then you can graduate with commerce.

Good luck