Science

Please refer to the link provided below for details regarding admissions in Jawaharlal Nehru University for M.Sc in environmental sciences. You should be able to download their brochure which contains important details like application dates, entrance tests (if any), admission criteria and process, fee structures, placement information, etc.
https://www.shiksha.com/university/jawaharlal-nehru-university-delhi-4225

You can migrate to another college provided your college has a tie-up with the target institute. Having a good academic record also helps. It will help push your application quicker. Before, you give up your seat with the current institute you should first block a seat in the target institute as a precaution. Consult with the admission authorities of your institute for further guidance.

A few science courses you can pursue after completing your class 12th with commerce and maths are as follows:
BMS (Bachelor of Management Science)
BCA (Bachelor of Computer Applications)
B.Sc (Applied Mathematics)
B.Sc (Statistics)
B.Sc (Animation and Multimedia)

YMCA, Haryana is the best option for you.

Please refer to the link provided below for details regarding admission in Vishwakarma Creative-I College (VCIC) for M.Sc in interior design. You should be able to download their brochure which contains important details like course eligibility, admission requirements and process, application dates, forms, fee structures, for a course in M.Sc. Interior design.
https://www.shiksha.com/design/interior-design/course/m-sc-in-interior-design-vishwakarma-creative-i-college-vcic-kondhwa-pune-191713

Please refer to the link provided below for details regarding entrance tests required for admission in M.Sc Fashion Designing. Important information like syllabus, last application dates, etc., are mentioned in the link provided below.
https://www.shiksha.com/design/exams/nift-entrance-exam/syllabus

Best coaching centers in Kanpur for UPCATET are as follows:
1) Vinayaka Classes & Home Tuitions
2) Selection Point
3) Mahendra Educational Private Limited - Mall Road
4) Career Power
5) Vidyamandir Classes - Kidwai Nagar

Hi Mudit,
You have to narrow down your choice basically, there could be many factors such as your budget, your career goals, the country you want to settle down in, admission requirements, etc. France, Spain, Netherlands, UK, Singapore, New Zealand, Australia, etc., could be good options also keeping note of the fact that you have a three-year degree.