Sounds like you allready have family that might help you, and that is a great relief to hear. Sad to hear about your father stance on things, and your mothers view. However, the fact that you have sisters that you can confide in is a great first step. Sadly, many find themselves facing what you are without such. I myself was lucky that when I came out as BI to my parents, they understood me. But I also know the flip side of that very coin. But, if you have older sisters, and grandparents who seem to understand you, and wanting to be there for you. I would suggest talking to your sisters first Dipper. And then your Aunt. Carrying it within you and supressing it leads to the selfhate you mentioned, and in the end, the longer you have to keep it in you, the worse it is likely to get. Look up local youth groups who support LGBT rights, trust me when I say that just being surrounded by people in the same boat as you helps alot.

And despite our differences Dipper, If there is anything I can do to help, send me a message.