The trick with any development is to split it up into small stages. Test and go on the the next bit.
I've been trying to make sense of your input all day and haven't had any luck.
Then why have you not posted a single line of code from that effort?
This forum is here to help people it is not a code writing sevice, we get kids here all the time trying to get us to do their homework for them.
You already have some code, you posted this at the start. Refactor (rearrange ) this code so it is in the form we are talking about. Forget for the moment the note off bit, just get it so that it works with the note on. Your loop function should have just one call in it. A call to a function that checks your hardware and if it finds a note needs to be sent it sends it, if not it returns. Write that test it, does it do exactly what you want? If not try and fix it or at least think about what it does not do what you want. Either way you then post the code you have and then you are in a state to implement the next step.
You have to take baby steps, not try and rush at it.