I'm not out to anyone, but my Mum will occasionally ask me things like 'Do you like girls?' and 'Are you gay?' It might be because of the fact that I frequently talk about how I wish I were a boy. I mean, being a girl isn't very fun. Theirs more peer pressure to be 'perfect' (Even In Uni!! it never ends!), periods, and puberty. None of that is very fun. But back to the point, my Mum already is suspicious of my sexuality, but she still says that things are 'Gay'. It really upsets me, but even at my age (22) I cant just call her out on it.
My parents do that too! My dad and mom have flat out asked if I was in a relationship with my best friend. I said no.... although that was a lie. I really am dating her. They are SUPER Catholic, so I can't come out. If it's super bugging you and you are on good terms with your Mum you could just talk to her about it. I don't know how your relationship is with her though. And if you're still questioning what you are, talking to her might help. I'm sorry if that was bad advice.... I'm very new at all this...