I was also really indecisive about my field and I wish I had just chosen the path I was most interested in at the time, knowing that it would probably change in the future (and that is ok!). I think the best thing you can do is be flexible!
I was a commerce student just like you and I faced the same situation after my 12th grade. At this time I took an option that could lead me into difference business study related fields which could allow me to specialize my interests and passion.
I recommend you go for a safe Undergraduate programme like a BBA or BCom which is a 3 to 4 year programme course (depending on your College/University's courses structure). During the first 2 years you will learn the basis of different commerce topics, like Marketing, Finance (accounting), Human Resources, Psychology etc. In the 3rd or 4th year is where you will need to choose which field you want to specialize your undergraduate degree in and based on this selection your last year courses will be determined and you will be learning courses catering to this field. Do not worry, the first two years will give you a good idea and help you build your interest to choose your specialization field within my undergraduate programme . The typical specialization options are Marketing, Finance, Psychology, Human Resources but some universities do offer different variety of specializations, so do some research on the university before applying into these programmes.
I personally would choose Marketing or Finance as the main specializing field in your 4th year of the Undergraduate programme as they offer more opportunities for jobs and further studies like MBA, ACCA , CPA etc.
Hope this helps! Goodluck.