You ask what you should do & say you haven't done any good for anyone, well like it or not here's my comments & advice.
1) you helped people via music & computer knowledge & by doing as your parents wanted even though you knew engineering wasn't what you wanted.
2) now if you had wanted to be an engineer or had any real intention of being one you obviously have the brains to have done it 3 years ago, you could have gotten help with the maths!! You chose not to.
3) you have to decide whose life you're living, yours or your parents?
4) you have to decide what you want, obviously it's music & computing!!!!
5) you need to see if you can transfer any subject units over to a computing degree, if yes, then you decide, if no then you decide what other jobs you could do that you could use computing &/or music.
6) youi have to accept that parents are human & many parents make their kids do courses that are wrong for them, but your future is in your hands, only you can make the necessary decisions to change the path your life in is on & go forward happily.