Last time I checked your mum wasn't a doctor/T too.

Seriously though, it's great that you are considering getting the help you need. Mayby an honest doscussion with your parents might help. You don't need to tell them it's because of SI. Mayby even write a letter to them? that's what I was doing when I wasn't able to calmly and reasonably explain to my mum stg. Sounds a bit weird maybe but she never let me finish what I was trying to say otherwise (not for lack of trying, but it just didn't get through to her) and this was a way for me to be really heard.
Just please, don't give up.