To become a software engineer, you can do B. Tech in computer science or B.E. in computer science otherwise you can also go for B.Sc in computer science and MCA courses. For better colleges in India, you should appear for JEE examination to seek admission at renowned IIT.
Generally, there are three options given to the class 11th students while opting for subjects which are pure science, or science with mathematics and the last one is pure science and mathematics as an optional subject. You can appear for JEE examination even if you are a PCB student but once you clear the examination and even if your scores are good, most of the colleges have fixed eligibility criteria of mathematics as a compulsory subject in class 11th and 12th. Hence, at times your clearing JEE is of no use. Therefore, you should take Physics, chemistry and mathematics in 11th and 12th. In connection with this, you can opt for Information Practices (IP) as an additional and optional subject that would develop your basics. After that, if you feel the need to opt for biology and having a knack for it then you can even take it as an optional subject, which would also give you another choice for appearing in NEET exams, but as per my advice, it sounds difficult.
Also to develop skills at some basic levels you can join some of the coding camps and other classes to enhance your basics and provide you with an edge over other students.