Maybe just chillax.
when you ask a chubby person "are you fat?"/"would you consider yourself fat?" there is a certain disconnect from the idea of "fat" and a person who "is fat".
If you are confused then you are bisexual. That's not an "accusation" it's a place for you to safely inhabit while you relax and take a breath and let yourself be you for a while.
Go out and meet people, meditate (or just spend relaxed time by yourself without distractions), be honest with yourself, who you really are will eventually start giving you signs once you clean out the "clutter" piece by piece.