I want to travel but I am worried how my family will cope..?

i'm 19 and have just done my first year at uni and i am looking into all these amazing travel opportunities and tours - it's all i can think about at the moment. but i feel really anxious and depressed about it because of my family situation at home.

long story short my younger sister has a lot of minor mental disorders, aspergers, anxiety, phobias etc and is out of contact with her friends and not at school at the moment. while she doesn't have any physical difficulties or anything, she's still very reliant on my mum who is absolutely great and very patient with her. my dad however does not really understand her needs and anxieties, and is not the kind of person who likes to talk about feelings and stuff, and is always very distracted with work. no one's fault, just the way things are.

it is one thing being away at university as we skype every week, plus i visit home every 3-4 weeks too. my worry is that i feel that i am my sister's only friend and that between my sister and my dad my mum would have a very hard time without me there, as we are very close.

it's not that my family would ever actively hold me back from doing what i wanted, but because i get really worried about how they would cope without me for that long, and being so far away, i don't feel like i have the freedom to see the world at my own pace and do the things i want to do.

i guess i just wanna know what people make of this.