Hey Aiden, it's very easy for people to judge because they don't want to think or actually attempt to understand. I know it's hard to not pay attention to what people are saying, but the only people that matter in your life are the ones that accept you and love you. I'm sorry your mum is being difficult, it can sometimes be hard for the older generation to accept that there's more than just two genders.
You are such a brave and amazing individual for being able to come out to anyone at all at such a young age. Honestly, it's the best time to do it as well, it's definitely hard but it's the easiest time to get the correct support and help to get you where you want to be.
I can't say it'll end, but I can say that it will improve over time, the world is evolving and becoming more open and understanding and you'll learn to filter out the nasty and ignorant comments that you don't want to hear. You'll also start to see some of the really good people out there too, the ones that talk to you and make you love yourself and the time you spend with them. Believe me, there's a lot of them out there.
Advice on what to do: this is a hard one, because I've never been through what you're going through but I have been suicidal before and it was close to your age. It's hard to deal with because of all the pressures and your body and mind is undergoing changes that may or may not be usual for people around you, but, I can say this: keep those that are precious to you close, and the interests and hobbies that you have, just as close. Fill your time with them, excel at them, become so great at them that when people start noticing you, they notice you for your talent and not for anything else. If you don't have anything you really enjoy doing - it's perfectly fine too - you just spend that time with the people you care for (your boyfriend, friends, family, whomever else) and you'll see that everything else really doesn't matter. As someone that has been around a fair while - the things that are most important are the people you love being with, not money or possessions and definitely not what others think. They're not worth your time or effort to consider them, they're wasted on the world and maybe, just one day, they'll open their eyes and realise that being cruel and horrible has gotten them nowhere and that's the reason they're so lonely in life.
I want you to realise that you are a REALLY amazing person and that you're going to be fine. I promise you this. Believe in yourself.
Sending you strength.