As a person who left her home and family to move to a city and state she had never visited before, I can relate to your concerns of needing support, and how important a role family plays.
While I moved away from my family for a job, and you are concerned over losing your family due to religion, the good news is you will be able to find support in the same place I found support; the Church.
I would encourage you to start taking baby steps to develop a relationship with the priest at the OCA parish you visited. Try to make an appointment with him to meet on your day off. Even if you can't meet in person, you can talk over the phone. While your journey to the Orthodox Church may be longer than some, it is still something that is attainable.
Talk to the priest about doing a "Reader Service" by yourself at home for the weeks you can't get to the Church for Divine Liturgy. Even if you are only able to make it the Church for Divine Liturgy once every other month, that is better than nothing.
The other reason you should consult the priest is that he may know of someone who has a room or apartment you could rent that is closer to the church, or at least outside of your sister's house. Even if he doesn't know of someone today, by making him aware of your situation, he can be on the look out in case anything comes up in the future.
By developing a relationship with the priest, he can introduce you to other people who can build up your network of support. He can also be there for you when you tell your family, and to help you deal with their reaction.
I know it may seem strange to reach out to someone you barely know, and ask them for help. This is what they are here for. To guide the flock, and to lead people to Christ.