Your chances of admission into any college is determined by two factors : 1. What you are , 2. How you are different from the other applicants.
Indian IT is over represented in every B-Schools, considering in the past decade IT was the only employment available to Indian students and we all jumped in.
Now when you speak of top B-Schools like ISB, IIMs, or any of top 10 US and Europe Schools, they will always have a over-crowded Indian IT and Male applicant pool, with 700+ GMAT. Every one is having 3+ exp, from an Engineering college (except IITs nothing else is recognized) and every one has put NGO experience or done some leadership activity. From an AdCom prospective, think how they will separate you out from Crowd ? It is your application.
A good application talks about how enriched your past was, how your past experience guided you take decision to go for MBA, how do you see yourself in future, how the school will help you achieving your ambition, and what the school will get in return from you ( a lot-to-learn from Classmate, a reputed alumnus). You will be given ample opportunity to speak through your Essays, but you must have something different to speak. This prepares you for the interview as well.
Do not bluntly say that you want to quit IT. You did 4 years bachelor, then took up IT job and within 3 years you want to quit ? The question would be why ? Your interest in your Shop doesn't sound promising. Your job description in your shop "to keep track of the stock of medicines and contact appropriate distributor" is not exciting enough. And do you need an MBA for that ? I am sure, you have more to say and You have a clear a vision - where do you want to take your shop and when. Talk about it, and If your words sound promising, then you are "in".
You are only 2.6 years experienced, you still can add much more value to your resume. Do not stick to ISB, have your options open. If you want to stay in India, you can consider IIM A. B,C, XLRI, SPJ.
And yes, your application is competitive. It is the confidence that matters.
I am no expert, but I do come from business family and I understand - do not invest, unless your return justifies it.
"Appreciation is a wonderful thing. It makes what is excellent in others belong to us as well."
Press Kudos, if I have helped.