This may help your mom:
http://nickgorton.org/ "Medical Therapy and Health Maintenance for Transgender Men"
It was written for health care providers who are just learning about how to treat transgender clients, and it contains statistics, such as "administering HRT reduces suicide rates by 2000%" (1% of post T trans men vs 20% of pre T trans men are suicidal, according to the book.) If she has more information about the benefits of HRT, maybe she'll be more supportive of you starting. It sounds like she wants the best for you, but she just doesn't understand or know how to cope with it.
Don't give up. Life is difficult for everyone, and no one understands anyone else's situation and perspective perfectly. It's your decision of course, but my advice is to do what you need to do to stay healthy first, and then try to work with your mom to help her with her own fears. Your first responsibility is to your own well being. After that, educating the people in your life is worthwhile because we all need each other, and the more people you have on your side, the better. Just because your mom is against you taking T, doesn't mean she's against you; she's probably just ignorant and scared. Taking care of yourself first may involve patience and strategy, i.e. you may want to find a job and a place to live before you start T if it's likely that you'll get kicked out of your house for doing so, but you can get through it. And when you do get through it, your mom will likely see that you're better off, and it seems like that's what she wants. So, take care man and good luck!