Dear Chandraveer, First of all, dont be sad for past. You can still change your future according to your dreams. Yes you can. You wanna be a doctor and still you can be a doctor but the difference is that in Engg. a doctor dont check the patients. I am telling about the research fields of your core branch Biotech. You can enter a research institute (CSIR, IIT, IISc, IISER etc.) as a research assistant and soon you will be a Doctorate degree holder after you present a thesis report in your research area. If you have any further doubt please reply me. Best of Luck.