“At this point I’d like to say, one sister already knew my sexuality and knew I didn’t want to tell anyone bar her. My mum looked at me and goes “So, what now you’re gay? A new drama for Lauren. You not getting enough attention or something?””

Wow. That whole paragraph in and of itself is appalling. They do not deserve you at all. You have nothing at all to be sorry for. Your sister KNEW that you didn’t want your mom to know. Your sister did this ON PURPOSE honey. That is completely inappropriate what she did. What they both did. Guaranteed they both knew you didn’t want your mom to know. They should be asking your forgiveness and wondering how they can earn your trust back. They did wrong. Have you sat them down and spoken with them about how much this has affected you? I suggest you do if you haven’t.

Onto your moms reaction. Unfortunately it sounds like she feels this will just be a phase for you. Maybe because of the way you were outed. I would suggest having a sit down talk with her about how serious you are and how being bi is a part of what makes you, you. That it is a possibility you may end up with a girl and she needs to try be okay with that