From what I have seen it's rare for T to cause a major problem and if it does it's with the female anatomy. And so I plan on eventually getting hysterectomy and oophorectomy to stay on the safe side (after a year on T or so, don't think I can do it sooner). But this kind of thing worries my mother and I am not sure how to explain that the risks are very low and especially after removing female anatomy and breasts there isn't much to worry about? And I presume even if it is done after a year the chances of anything going wrong still decreases greatly?

EDIT: Ultimately it's my choice to go on T but I need people not to worry about me. 

Just get your Mom to the point she will talk about it with a doctor that has experience prescribing hormones to to trans people. That is the only thing you can do.

That is what you should do anyways. Each person has different risks, and your own risk for anything that could happen is dependent upon your own health situation.